Contactless ic card system
AssigneeSony Corporation
InventorShigeru Arisawa
Life of this patent
Estimating the term…
Abstract
In a contactless IC card system, a modulating circuit manufactured in an IC form is operable at a high power efficiency. The demodulating apparatus is configured to include: first signal output means for outputting a first output signal having a predetermined phase with respect to that of an input signal, a second signal output means for outputting a second output signal having a predetermined phase with respect to that of the input signal, gate means for gating at least the second output signal, calculation means for adding, or subtracting the first output signal and the second output signal; and control means for controlling the operation of the gate means in response to a logic level of input data.
Claims15
1-22. (canceled)
An amplifying circuit in which an operation of a field-effect transistor is switched in response to an input signal so as to output a power-amplified signal of said input signal from said field-effect transistor, comprising:
- a drive circuit for switching the operation of said field-effect transistor by applying a voltage to a gate of said field-effect transistor, said voltage being higher than or equal to a source-to-drain voltage of said field-effect transistor.
25-27. (canceled)
A transmitter apparatus for amplitude-modulating input data to thereby transmit the amplitude-modulated input data, comprising:
- a first modulating circuit for producing a first amplitude-modulated signal in response to said input data;
- and
- a second modulating circuit for producing a second amplitude-modulated signal made of a carrier wave having a phase opposite to that of said first amplitude-modulated signal, wherein
- each of said first modulating circuit and said second modulating circuit comprises:
- first signal output means for outputting a first output signal having a first predetermined phase with respect to that of an input signal;
- a second signal output means for outputting a second output signal having a second predetermined phase with respect to that of said input signal;
- gate means for gating at least said second output signal;
- calculation means for adding, or subtracting said first output signal and said second output signal;
- and
- control means for controlling the operation of said gate means in response to a logic level of input data.
A transmitter apparatus for amplitude-modulating an input signal to thereby transmit the amplitude-modulated input signal, comprising:
- a first modulating circuit for producing a first amplitude-modulated signal in response to said input signal;
- and
- a second modulating circuit for producing a second amplitude-modulated signal made of a carrier wave having a phase opposite to that of said first amplitude-modulated signal in response to said input signal, wherein
- each of said first modulating circuit and said second modulating circuit comprises:
- a variable attenuator provided at an output terminal of a power amplifying circuit, for attenuating a power-amplified result of said power amplifying circuit in response to an input signal.
A demodulating circuit comprising:
- clamping means for clamping an input signal;
- and
- band limiting means for removing a component of said input signal from an output signal of said clamping means.
A demodulating circuit, comprising:
- signal processing means for producing first and second input signals having phases different from a phase of an input signal by approximately 180 degrees;
- first clamping circuit for clamping said first input signal;
- second clamping circuit for clamping said second input signal;
- first band limiting means for removing a component of said first input signal from an output signal of said first clamping circuit;
- second band limiting means for removing a component of said second input signal from an output signal of said first clamping means;
- and
- calculating means for adding, or averaging an output signal of said first band limiting means and an output signal of said second band limiting means.
A demodulating circuit, comprising:
- signal processing means for producing first and second input signals having phases different from a phase of an input signal by approximately 180 degrees;
- a first clamping circuit for clamping said first input signal;
- a second clamping circuit for clamping said second input signal;
- first band limiting means for removing a component of said first input signal from an output signal of said first clamping circuit;
- and
- second band limiting means for removing a component of said second input signal from an output signal of said second clamping circuit;
- and
- calculating means for adding, or averaging an output signal of said first band limiting means and an output signal of said second band limiting means.
Dependencies are inferred from the claim text.