Current Mirror Layout Matching

Current Mirror Layout Strategies 13 where 1. DH is the minimum separation, usually 4 lambda, between the two drain diffusions, D1 and D2. 2. VT1 and VT2 are the threshold voltages of the two transistors of equal sizes WL 3. VTNis the threshold voltage at the coordinate refer- ence point O in Fig. 3a. If the equivalent VT equation 1 is applied to the Type I interdigitized layout of Fig. 3

Layout Tradeoffs Matching often involves tradeoffs - Increased channel length - Increased circuit area - increased power dissipation, reduced speed, Determine required level of matching - Minimal 3Vos gt 10mV, 3IDID gt 2 Unit elements, matched orientation, compact layout - Moderate 3Vos gt 2mV, 3

A current mirror replicates the input current of a current sink or current source as an Example 16-1 - Aspect Ratio Errors in Current Mirrors A layout is shown for a one-to-four current amplifier. Assume that the lengths are Current gain matching - good as long as v DS4 v DS2 I Bias IO M3 M2 M1 i i M4 FIG. 310-11 V DD i o V DD

Lecture 06 Current Mirrors Analog IC Design Dr. Ryan Robucci Department of Computer Science and Electrical Engineering, UMBC Spring 2015 predicts good current matching behavior V C 2 V on 2 V TH big O V outmin 2 V on V TH big O R in 2 1 g m Input Voltage V TH1 V OV1 V TH3 V OV3 2 V TH 2 V

a Design in Cadence the simple current mirror from the prelab. If needed, modify the design so that it meets the given specifications. b Generate the plots of Figure 5-5 and Figure 5-6 fo r this design. Determine the compliance voltage, low frequency output impedance, and comment on accuracy. c Layout the current mirror. Run post layout

This paper proposes a new current mirror layout technique to improve matching characteristics in the presence of parameter gradient. Effects of threshold gradients across a mirror on the matching characteristics of current mirrors are discussed. New and the existing layouts are compared with computer simulations for threshold voltage gradients at all angles across the active area. Results show

A basic current mirror is depicted in Fig. 2. The input port is at the drain of transistor M1, the output is at the drain of transistor M2 and the sources are common. Five different common layouts for this current mirror are shown in Fig. 3. Fig. 3a shows the simple layout technique. Although parameter gradients that occur in the direction

Circuit engineers and layout designers are aware of these issues when matching devices in current mirrors. One method is to use is Pelgrom's law and make devices bigger. Pelgrom et al, 1999 This improves Vt matching and noise performance, but at a cost of increased area and reduced bandwidth. Another is to match devices geometrically.

2. Matching Techniques. Matching - is a very useful technique in IC layout targeting similar performance from every device in analog design. Let's take a look on a very simple example - a current mirror 12. Reference current I r e f I_ref I re f is copied from device A 2 fingers, 2 multipliers to the device B 2 fingers, 4 multipliers producing an output current I o u t 2 I r e f I

Matching Techniques in Analog Layout - Key Types and Best Practices. When we work with analog circuits, designs like differential pairs and current mirrors often come into play. I've learned that matching device characteristics, such as the threshold voltage Vt, is crucial. You'll find that even tiny threshold differencesjust a few