US 8,427,587 B2 · Tracking filter and associated calibration device

Abstract

A tracking filter includes a first buffer, an impedance transformer, an inductor, a first capacitive unit, a second capacitive unit and a second buffer. The first buffer has an input terminal for receiving an input signal. The impedance transformer is connected with an output terminal of the first buffer. The inductor is connected with a second terminal of the impedance transformer. The first capacitive unit is interconnected between the impedance transformer and a ground terminal. The second capacitive unit is interconnected between the inductor and the ground terminal. The second buffer is connected with the inductor for generating an output signal. When specified values of the impedance transformer, the first capacitive unit and the second capacitive unit are simultaneously increased, an operating frequency of the output signal is decreased, so that a gain value of the output signal to the input signal is maintained constant.

Claims14

Dependent claims

A tracking filter of a TV tuner, the tracking filter comprising:

a first buffer having an input terminal for receiving an input signal;
an impedance transformer having a first terminal connected with an output terminal of the first buffer;
an inductor having a first terminal connected with a second terminal of the impedance transformer;
a first capacitive unit interconnected between the second terminal of the impedance transformer and a ground terminal;
a second capacitive unit interconnected between a second terminal of the inductor and the ground terminal;
and
a second buffer having an input terminal connected with the second terminal of the inductor and an output terminal for generating an output signal,
wherein when specified values of the impedance transformer, the first capacitive unit and the second capacitive unit are simultaneously increased, an operating frequency of the output signal is decreased, so that a gain value of the output signal to the input signal is maintained constant.

5 more elements

A digital calibration device of a TV tuner, the digital calibration device comprising:

a tracking filter comprising:
a first buffer having an input terminal and an output terminal;
an impedance transformer having a first terminal connected with the output terminal of the first buffer;
an inductor having a first terminal connected with a second terminal of the impedance transformer;
a first capacitive unit interconnected between the second terminal of the impedance transformer and a ground terminal;
a second capacitive unit interconnected between a second terminal of the inductor and the ground terminal;
a resistive unit interconnected between the first terminal and the second terminal of the inductor;
and
a second buffer having an input terminal connected with the second terminal of the inductor;
a frequency detector connected with the inductor for receiving a first oscillation signal with a first oscillation frequency and receiving a local oscillation signal with a reference frequency, thereby generating a counting signal;
and
a controlling circuit for receiving the counting signal and generating a control signal according to the counting signal, wherein according to the control signal, a specified value of the impedance transformer, the first capacitive unit or the second capacitive unit is adjusted, so that the first oscillation frequency of the first oscillation signal is close to the reference frequency.

9 more elements

Dependencies are inferred from the claim text.

Tracking filter and associated calibration device

Life of this patent

Tracking filter and associated calibration device

Life of this patent

Abstract

Claims14