Track and hold circuit and related receiving device with track and hold circuit employed therein

A receiving device, comprising:

• a front end circuit, arranged to receive a first signal and generate a second signal according to the first signal, wherein a frequency of the first signal is different from a frequency of the second signal;
• a back end circuit, coupled to the front end circuit, for processing the second signal;
• and
• a track and hold circuit, coupled to the front end circuit, comprising:
• a gain control circuit, arranged to provide a gain value upon the second signal according to a set of control signals, the gain control circuit comprises:
• a first resistor-based network, arranged to selectively provide a first resistance between a first signal receiving terminal receiving the input signal and a first input terminal of an operational amplifier according to the set of control signals;
• and
• a second resistor-based network, arranged to selectively provide a second resistance between the first input terminal of the operational amplifier and a first output terminal of the operational amplifier according to the set of control signals;
• the operational amplifier, arranged to generate an output signal according to the second signal and the gain value;
• and
• a capacitor, arranged to hold the output signal between the first input terminal and the first output terminal of the operational amplifier;
• wherein when the track and hold circuit is operating, a first terminal of the capacitor is consistently coupled to the first input terminal of the operational amplifier, and a second terminal of the capacitor is consistently coupled to the first output terminal of the operational amplifier;
• and when the first resistance is not provided between the first signal receiving terminal and the first input terminal, and the second resistance is not provided between the first input terminal and the first output terminal, the track and hold circuit holds the output signal by the first capacitor.

A receiving device, comprising:

• a front end circuit, arranged to receive a first signal and generate a second signal according to the first signal, wherein a frequency of the first signal is different from a frequency of the second signal;
• a back end circuit, coupled to the front end circuit, for processing the second signal;
• and
• a track and hold circuit, coupled to the front end circuit, comprising:
• a gain control circuit, arranged to provide a gain value upon the second signal according to a set of control signals;
• an operational amplifier, arranged to generate an output signal according to the second signal and the gain value;
• and
• a capacitor, arranged to hold the output signal between a first input terminal and a first output terminal of the operational amplifier;
• wherein there is no switching element connected to the capacitor in series between the first input terminal and the first output terminal of the operational amplifier, and the gain control circuit selectively provides a first resistance between a first signal receiving terminal receiving the second signal and the first input terminal of the operational amplifier, and selectively provides a second resistance between the first input terminal of the operational amplifier and the first output terminal of the operational amplifier according to the set of control signals;
• and when the first resistance is not provided between the first signal receiving terminal and the first input terminal, and the second resistance is not provided between the first input terminal and the first output terminal, the track and hold circuit holds the output signal by the first capacitor.