US 5,963,156 A · Sample and hold circuit and method with common mode differential signal feedback for converting single-ended signals to differential signals

Abstract

A sample and hold (S/H) circuit with common mode differential signal feedback for converting single-ended signals to differential signals includes a feedback loop for the input switched capacitor circuit to ensure that the input common mode voltage for the differential amplifier is maintained at a known value during the hold phase of operation. The feedback loop consists of a three-input error amplifier which monitors the two voltages at the differential input terminals of the differential amplifier in relation to the common mode reference voltage and generates a feedback voltage which is applied to the input terminals of the input switched capacitor circuit during the hold phase of operation. If both of the differential input terminal voltages are either more negative or more positive than the common mode reference voltage then the feedback voltage generated by the error amplifier is made more positive or negative, respectively.

Claims26

Dependent claims

An apparatus including a sample and hold (S/H) circuit with common mode differential signal feedback for converting a single-ended signal to a differential signal, comprising:

an input switched capacitor circuit configured to receive a plurality of sample and hold control signals, an input reference signal and a feedback reference signal and in accordance therewith receive and sample a single-ended input signal and in accordance therewith provide a differential input signal;
and
a feedback circuit, coupled to said input switched capacitor circuit, configured to receive said hold control signal, said input reference signal and said differential input signal and in accordance therewith provide said feedback reference signal.

An apparatus including a sample and hold (S/H) circuit with common mode differential signal feedback for converting a single-ended signal to a differential signal, comprising:

a sampling circuit configured to receive a plurality of control signals and in accordance therewith
receive and sample a single-ended input signal during a sample phase and receive a variable feedback voltage during a hold phase and in accordance therewith provide a sampled signal, and
convert said sampled signal to an intermediate differential signal in accordance with said variable feedback voltage during said hold phase, wherein said intermediate differential signal includes a common mode input voltage;
and
a feedback circuit, coupled to said sampling circuit, configured to monitor said common mode input voltage and a common mode reference voltage and in accordance therewith provide said variable feedback voltage, wherein said variable feedback voltage is adjusted to cause said common mode input voltage to remain substantially constant in relation to said common mode reference voltage.

2 more elements

A sample and hold (S/H) method of converting a single-ended signal to a differential signal with common mode differential signal feedback, said method comprising the steps of:

receiving a plurality of sample and hold control signals, an input reference signal and a feedback reference signal and in accordance therewith receiving and sampling a single-ended input signal and in accordance therewith generating a differential input signal;
and
receiving said hold control signal, said input reference signal and said differential input signal and in accordance therewith generating said feedback reference signal.

A sample and hold (S/H) method of converting a single-ended signal to a differential signal while maintaining a substantially constant common mode voltage, said method comprising the steps of:

receiving and sampling a single-ended input signal during a sample phase to generate a sampled signal;
receiving a variable feedback voltage during a hold phase;
converting said sampled signal to an intermediate differential signal in accordance with said variable feedback voltage during said hold phase, wherein said intermediate differential signal includes a common mode input voltage;
and
monitoring said common mode input voltage and a common mode reference voltage and in accordance therewith adjusting said variable feedback voltage, wherein said adjusting of said variable feedback voltage causes said common mode input voltage to remain substantially constant in relation to said common mode reference voltage.

2 more elements

Dependencies are inferred from the claim text.

Sample and hold circuit and method with common mode differential signal feedback for converting single-ended signals to differential signals

Life of this patent

Sample and hold circuit and method with common mode differential signal feedback for converting single-ended signals to differential signals

Life of this patent

Abstract

Claims26