Method of precharging a switchable filter
A switchable capacitor assembly is provided that includes a first terminal, a second terminal, a first resistor, a first switch, a capacitor operatively connected between the first switch and the second terminal, a voltage follower operatively connected between the first terminal and the first resistor, the first resistor being operatively connected between the voltage follower and the first switch, and a second switch configured to short circuit the first resistor. The first switch is configured to toggle between two states including a first state where the switch operatively connects the capacitor to the first resistor and a second state where the switch operatively connects the capacitor to the first terminal.
1 . A switchable capacitor assembly comprising:
a first terminal,
a second terminal,
a first resistor,
a first switch,
a capacitor operatively connected between the first switch and the second terminal,
a voltage follower operatively connected between the first terminal and the first resistor, the first resistor being operatively connected between the voltage follower and the first switch, and
a second switch configured to short circuit the first resistor,
where the first switch is configured to toggle between two states comprising:
a first state where the switch operatively connects the capacitor to the first resistor and
a second state where the switch operatively connects the capacitor to the first terminal.
2 . The switchable capacitor assembly according to claim 1 , wherein the voltage follower comprises an amplifier.
3 . A switchable filter comprising:
a signal path having a signal input and a signal output,
a second resistor operatively provided between the signal input and the signal output and
the switchable capacitor assembly according to claim 1 , where the first terminal is connected to the signal path and where the second terminal is connected to a first predetermined potential.
4 . An assembly for testing a device, the assembly comprises:
a plurality of signal sources,
a plurality of switchable filters according to claim 3 , and
a monitoring device configured to monitor the operation of the device,
where:
the device has a plurality of inputs and an output,
each switchable filter is operationally connected between a separate source and a separate input,
the output is operationally connected to the monitoring device.
5 . A method of switching the switching capacitor assembly according to claim 1 , the method comprising the steps of:
a) connecting the second terminal to a first predetermined potential,
b) providing a second predetermined voltage to the first terminal while the second switch does not short circuit the first resistor,
c) operating, after step b), the second switch to short circuit the first resistor and
d) operating the first switch from the first state to the second state.
6 . The method according to claim 5 , wherein the switchable capacitor assembly forms part of a switchable filter also comprising:
a signal path having a signal input and a signal output,
a second resistor operatively provided between the signal input and the signal output where the first terminal of the switchable capacitor assembly is connected to the signal path and where the second terminal is connected to a first predetermined potential,
the method comprising the steps of:
providing a second predetermined voltage to the signal path, and
operating the first switch from the first state to the second state.
7 . The method of operating according to claim 6 , where a plurality of the switchable filters form part of an assembly for testing a device, the assembly comprising:
a plurality of signal sources, and
a monitoring device configured to monitor the operation of the device,
where:
the device has more a plurality of inputs and an output,
each switchable filter is operationally connected between a separate source and a separate input, and
the output is operationally connected to the monitoring device,
the method comprising the steps of:
at least one source feeding a varying voltage to the device via a switchable filter,
the monitoring device monitoring an output of the device,
maintaining the voltage output of the at least one source at a predetermined level, and
operating the first switch of the switchable filter into its second state.
8 . The method according to claim 6 , further comprising the step of, prior to the step of operating the first switch, operating the second switch to short circuit the second resistor.
9 . The method according to claim 6 , further comprising the step of, prior to the providing of the second predetermined voltage to the first terminal or the signal path, varying a voltage on the first terminal.