The common gate CG stage Example cascode stage
- Slides: 10
The common gate (CG) stage Example: cascode stage constant voltage signal source low resistance signal output resistance and capacitance of the signal source CG used as a summing stage P. Bruschi – Design of Mixed Signal Circuits 1
Frequency response of the common gate stage small-signal circuit with parasitic capacitances P. Bruschi – Microelectronic System Design 2
Frequency response of the common gate stage current division between Rin and zs P. Bruschi – Microelectronic System Design 3
Frequency response of the common gate stage P. Bruschi – Microelectronic System Design 4
Noise contribution of a CG stage zs=cp//rs Every time we have a floating current source, we can split it into two sources with one terminal at ground P. Bruschi – Microelectronic System Design 5
Noise contribution of a CG stage As far as zs is much larger than Rin=1/gm-cg, the contribution of MCG noise current source is strongly attenuated P. Bruschi – Microelectronic System Design 6
Noise contribution of a CG stage P. Bruschi – Microelectronic System Design 7
Noise contribution of a CG stage P. Bruschi – Microelectronic System Design 8
Noise contribution of a CG stage bode diagram of in-out/in-gc The pole is the same of the frequency response (cut-off frequency of the stage) P. Bruschi – Microelectronic System Design 9
Typical operating conditions of a CG stage in integrated circuits 1. 2. 3. P. Bruschi – Microelectronic System Design 10
