Pseudo nmos inverter pdf

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The dividing point between binary and thermometer decoding is determined by the specific application. The voltage at the node increases non-linearly with N, where N is the value of the digital input The PCNTRL signal generated at the node is connected to the variable capacitance delay element to enable the delay element to provide a specified delay to an input signal having coarse timing edges.

As will be discussed below, delay element provides finely tuned output signal see Figure 3. However, although both the voltage and the current from the DAC are inversely related to N, the delay reflected to the delay element is proportional to the digital input The delay element of the present invention, shown in Figure 5 will flow be discussed.

The pseudo-NMOS circuit shown in Figure 5 provides fine tuning of a negative timing edge of an input signal A pseudo-PMOS circuit is shown in Figure 6 and provides fine tuning of a positive timing edge of the input signal Like reference numbers in these figures indicate identical or functionally similar elements.

As discussed above, an independent variable N represents the digital input to the DAC and the transfer function between the output signal of the current mirror and the digital input is inversely related to N.

The PCNTRL signal regulates the charging current current mirrored from the DAC into the variable capacitance and is used for adjusting the delay of the buffer For the present invention, the PCNTRL signal is also used for nulling process variations and thus obtaining a nominal time delay.

By changing the mirror ratio of the DAC, the charging current changes. The time to charge the internal node is inversely proportional to the charging current. The source and drain electrodes are shorted together. The gate capacitance is effectively switched in or out of the circuit by driving the source-drain node to the negative or positive supply voltage, respectively. Thus, small finely controlled amounts of capacitance can be added to the internal node via digital control.

As is evident to those skilled in the art, the size of the capacitor FET is chosen corresponding to the fine timing resolution required by an application of the present invention. The number of capacitors attached to the internal node is determined by the dynamic range requirements. Since the delay of the element is linearly proportional to the capacitance of the internal node, this technique offers a linear relationship between the programmed capacitor setting and the delay of the circuit.

For the present invention, the higher order capacitors are implemented as capacitor banks in order to reduce non-linearities. Further embodiments of the present invention include pseudo-PMOS circuits for controlled delay of positive timing edges see Figure 6.

Referring again to Figure 5, the PNMOS delay element comprises inverter and inverter , and various capacitor banks , , , , and , which are shown generally at , driven by decode circuitry and connected in parallel to an internal node Adjusting this voltage modulates the charging of the capacitance on the internal node An inverted output signal from the inverter is delayed on node by the previously mentioned capacitor banks that are switchably connected to the node.

The lower order capacitor banks FET banks comprised of less than 8 FETs are rendered active by control signals G1-G3 see lines , and , respectively. Once active, i. Control signals G1-G3 are Boolean coded to apply additional capacitance to the node in a linear fashion.

The control signals G4 and G5 are thermometer encoded to minimize device mismatch due to process tolerances. Lines , , , and comprise the control bus discussed above in connection with Figure 3. A first capacitor bank comprises one NMOS FET with its gate connected in parallel to the node as well as a short-circuited source-drain node which is controlled by a gate-control input signal G1 on line G1 is logically inverted and buffered by an inverter The gate-control input signal G2 on line is inverted and buffered by an inverter and controls the short-circuited source-drain node of a pair of parallel connected FETs forming the capacitor bank The capacitor bank is connected to the node so as to control the next significant bit on the node.

A gate-control input signal G3 on line , which is inverted by an inverter , controls a group of four FETS forming a capacitor bank Capacitor bank is connected in parallel to the node via the gates of capacitor bank so as to control the next significant bit of the node. A logical NOR gate of a gate-control input signal G4 on line and gate-control input signal G5 on line controls the source-drain node of a capacitor bank An inverter provides an inverted output signal of the gate-control input signal G4.

Output signal controls the source-drain node of a capacitor bank , comprising eight NMOS FETs that provide a capacitance delay for the next significant bit on the node An output signal of logical NAND controls the source-drain node of a capacitor bank Note that the FETs of the first four capacitor banks are arranged in a binary fashion, 1, 2, 4, 8 so as to achieve the programmed capacitance capabilities offered by a binary decode provided to inputs G1 through G3.

The thermometer decode is such that the three 8 FET capacitor banks, , and , turn on monotonically as the input signal G4 and the input signal G5 increase from a binary zero 00 2 to a binary three 11 2. The delayed signal on node provided by the capacitor banks is an input signal to the gate of an NMOS FET of the inverter The delayed data signal on node is then reinverted to provide a data output signal OUT which is logically consistent with the data input signal IN. This reversal of the control signal and input signals permits controlled delay of positive timing edges.

The delay line of the present invention will now be discussed. Specifically, a group of delay elements are serially arranged so that the data output from one delay element is connected to the data input of a next delay element. A portion of this group of stacked delay elements is used to add fine increments of delay to an input timing edge and another portion of this group of stacked delay elements is used to add coarse increments of delay.

A further portion of this group may be used for calibration. Referring now to Figure 7, a logic diagram is shown of the high level structure comprising a preferred embodiment of a delay line of the present invention. The delay elements , and comprise fine delay elements F 1 , F 2 , F n and delay elements , and comprise coarse delay elements C 1 , C 2 , The input signal which has coarse timing edges is applied to the input of element The number of delay elements is determined by the desired application of the delay line The number of fine delay elements F 1 , F 2 , Each fine delay element has a control input GF 1-n [] which corresponds to control bus of Figure 3 and lines G1-G5 of Figures 5 and 6.

The control inputs GF 1-n [] specify the amount of delay to be added by the corresponding fine delay element. Similarly, each coarse delay element has a control input GC 1-n [] which specify the amount of delay to be added by the corresponding coarse delay element. The final fine delay element F i and all coarse delay elements are tapped off at their respective outputs D[1], D[2], A nominal coarse delay is set for each coarse delay element by controlling the respective capacitor banks.

The bit size of the select bus is determined by the particular application. The delay line enables the fine delay generated by the delay elements F 1 , F n to be combined with the coarse delay generated by the coarse delay elements C Therefore, the Fine Edge FE output signal is derived from the coarse edge CE input after adding an appropriate amount of fine and coarse delay.

A select bus of N inputs S[1:N] , provides a digital control to select any of the N delay input signals D[1], D[2], In one embodiment of the present invention only one tap may be enabled at a time. The common pull-up FET with all open drain nodes "wired" electrically connected to it acts as an OR gate wired-OR allowing the active tap to propagate to the output. Because the present invention has applicability in Integrated Circuit IC test environments that require an ability to compensate for temperature, power supply and process variations, it is necessary to be able to isolate the behavior of a circuit-under-test from that of the test system.

The support circuitry comprises: 1 a data register which receives a digital value representing a desired time delay to be added to an input signal having coarse timing edges; 2 a RAM which provides the calibration memory for the fine delay aspect of the programmed digital delay; 3 a register bank which provides the calibration memory for the coarse delay aspect of the programmed digital delay; 4 decode circuitry for each of the fine and coarse aspects of the programmed digital delay to be input to the PNMOS wired-OR Tapped Delay Line to obtain a desired fine edge FE output signal; and 5 calibration circuitry to support various calibration procedures.

Figure 9 shows a block diagram of a time vernier , which is used to provide a well-controlled fine timing edge output from a coarse timing edge input. A data bus provides an input data signal to an alpha register The input data signal specifies a desired programmed digital delay which is stored in the alpha register It only takes a minute to sign up.

Connect and share knowledge within a single location that is structured and easy to search. This is a pretty tricky section to understand; the concepts surrounding this are intricate as well.

One is expected to analyse this entire concept from different perspectives for a solid understanding and that's where people get lost. Hence, a long answer; dissected and presented. Here, the author just wants to show how effective is the circuit as an inverter with varying the various parameters.

Like you said, the resistance will definitely change with Vds. I'll start with your characteristic figures. So, there's a constant current flowing to charge the output capacitance Vout to Vdd.

So, in order to lessen this effect, we reduce the width of the transistor length is generally constant for a design and not preferred to change so that the overall resistance of the device increases, ultimately giving low value of current to charge the Vout to Vdd. Hence, smaller is the width, lesser is the current, better is the output. The same relation is reflected in figure d , with respect to current. Less is the device size, lesser would be the current flowing the device. Now, let's understand the role of Vds in this circuit and in which part of analysis it plays an important role.

If you compare the values at the two sides, you observe that the let hand side is at a more negative value than right side Since Vout is less than Vtp. Hence, the value is at saturation initially. Note that, here the entire analysis is made with Vin held at 0V, hence we can't call this the characteristics of the circuit, since it individually analyses the PMOS device.

Image from Digital Integrated Circuits, 2nd edition, Rabaey. Now, observe figure c and compare it with the above figure. The regions defined in the above figure apply to your figure c as well approximately.

We scale the transistor widths up by the number of devices put in series. The geometries are left untouched for devices put in parallel. The pair is in parallel with C which is in series with a parallel combination of D and E.

Implementation of A. Dinesh Sharma Logic Design Styles. All-of-the-stars-sheet-music-ed-sheeran- sheetmusic-free. J-r-hampton-ecg-made-easy 6a.