Baseline restorer circuit

A baseline restorer circuit, the baseline restorer circuit comprising:

• a controller;
• a sample control circuit arranged to receive an input voltage signal that is output from a circuit stage comprising an amplifier, wherein the sample control circuit is configured to capture a sample of the input voltage signal at a sampling time in response to receiving a first control signal from the controller;
• an analogue processing stage arranged to receive the sample of the input voltage signal and a constant baseline reference voltage and selectively process the sample of the input voltage signal to provide an output voltage;
• a transconductance stage configured to convert the output voltage to a compensation current and supply the compensation current to an input of the circuit stage;
• and
• a change detector configured to monitor if the input voltage signal changes during a time interval around the sampling time, and if no change is detected in the input voltage signal during the time interval, the controller is further configured to transmit a second control signal to the analogue processing stage to control the analogue processing stage to process the sample of the input voltage signal,
• wherein the change detector comprises a change detector stage arranged to receive a digital signal output from an energy discriminator, wherein the digital signal is generated by the energy discriminator in dependence on a comparison of a level of the input voltage signal with at least one threshold value, the change detector stage configured to monitor if the input voltage signal changes during a time interval around the sampling time based on the digital signal.

A baseline restorer circuit, the baseline restorer circuit comprising:

• a controller;
• a sample control circuit arranged to receive an input voltage signal that is output from a circuit stage comprising an amplifier, wherein the sample control circuit is configured to capture a sample of the input voltage signal at a sampling time in response to receiving a first control signal from the controller;
• an analogue processing stage arranged to receive the sample of the input voltage signal and a constant baseline reference voltage and selectively process the sample of the input voltage signal to provide an output voltage;
• a transconductance stage configured to convert the output voltage to a compensation current and supply the compensation current to an input of the circuit stage;
• a change detector configured to monitor if the input voltage signal changes during a time interval around the sampling time, and if no change is detected in the input voltage signal during the time interval, the controller is further configured to transmit a second control signal to the analogue processing stage to control the analogue processing stage to process the sample of the input voltage signal;
• and
• a comparator arranged to receive a sample of the input voltage signal and the constant baseline reference voltage, the comparator configured to:
• compare the sample of the input voltage signal to the constant baseline reference voltage to determine a differential voltage value;
• and
• determine, using the differential voltage value, whether the sample of the input voltage signal is within an acceptable range of the constant baseline reference voltage;
• and
• output a fourth control signal to the controller, the fourth control signal indicating whether the sample of the input voltage signal is within the acceptable range of the constant baseline reference voltage, wherein transmission of the second control signal to the analogue processing stage to control the analogue processing stage to process the sample of the input voltage signal is further based on the fourth control signal indicating that the sample of the input voltage signal is within the acceptable range of the constant baseline reference voltage.