1. ADVANCED INTEGRATED CIRCUITS Eugenio Culurciello Spring 2005 Yale University SWITCHED CAPACITORS CIRCUITS

2. Continuous Time Continuous Value Analog circuits, op- amps, filters… Discrete Time Continuous Value Switched capacitors Continuous Time Discrete Value Asynchronous Digital Logic Discrete Time Discrete Value Synchronous Digital Logic

3. Switched Capacitors are often used in modern analog VLSI: Integrators both for voltages and currents Filters (many more advanced filters have been developed) Operational Amplifiers Comparators Noise-reduction circuits (CDS) Charge pumps Isolation circuits

4. Switched Capacitors Yes, but how do we implement switches?

5. Switched Capacitors And are the switches good? No! Because of charge injection due to gate charge which divides into 2 charges We need to cancel the added charge using a compensated switch – a simple technique!

6. Switched Capacitors And are the switches good? Other compensation techniques: differential signaling Pay attention to noise in the sampling capacitors! The noise power is kT/C!

7. Switched Capacitors Operational Amplifiers Comparators Integrators

8. Switched Capacitors CDS = noise reduction in image sensors removes offsets and fixed-pattern noise Michael will present a paper on this next Thursday Please remember to read the paper for discussion!

9. Switched Capacitors Charge Pumps

10. Switched Capacitors Charge Pumps

11. Switched Capacitors Isolation Amplifiers

12. Switched Capacitors Isolation Amplifiers