Radio circuit and control method of radio circuit

Details Radio circuit and control method of radio circuit Radio circuit and control method of radio circuit

2001-10-09

2004-11-30

Tieu, Binh (Department: 2643)

Telecommunications

Transmitter and receiver at same station

Radiotelephone equipment detail

C455S232100, C455S343200, C455S343500, C455S571000, C455S574000

Reexamination Certificate

active

06826418

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a radio circuit used for radio communication and the like and a control method of the radio circuit, particularly to reduction of the power consumption of a receiving circuit.
2. Description of the Related Art
A radio circuit requires an ability to receive a desired signal even when an interfering wave is input at a predetermined level range. One of deterioration factors of the receiving characteristic due to an interfering wave is deterioration of the receiving characteristic due to reduction of a gain caused by saturation of a receiving circuit due to an interfering wave at a strong level when the level of the desired signal is low.
FIG. 9
shows a basic configuration of a conventional radio circuit. In
FIG. 9
, the radio circuit comprises a receiving circuit
101
, a transmitting circuit
102
, a receiving RF filter
103
, a transmitting RF filter
104
, an antenna
105
, a local oscillator
106
, and a base-band circuit
107
. Signals having unnecessary frequencies out of signals received by the antenna
105
are reduced or attenuated by the receiving RF filter
103
, and then the remaining signals are input to the receiving circuit
101
. The receiving circuit
101
selects a signal with a desired frequency from the remaining signals in accordance with the output signal frequency of the local oscillator
106
, demodulates the selected signal, and outputs the demodulated signal to the base-band circuit
107
.
The transmitting circuit
102
modulates an output signal of the local oscillator
106
in accordance with a modulating signal supplied from the base-band circuit
107
to generate a transmission signal. The transmitting RF filter
104
reduces unnecessary frequency components from the signal transmitted from the transmitting circuit
102
. Then, the transmission signal is transmitted from the antenna
105
.
In the case of the above conventional radio circuit, power consumption of the receiving circuit
101
is continuously increased to expand the linear operation range in order to prevent the receiving circuit
101
from being saturated due to a strong-level interfering wave. Therefore, there is a problem that a large power consumption is generated even under a state of receiving no interfering wave.
SUMMARY OF THE INVENTION
The present invention has a purpose to provide a radio circuit and a control method of a radio circuit, in which a desired receiving characteristic can be achieved even when a strong-level interfering signal is received, but the power consumption of a receiving circuit when no interfering wave is received can be decreased.
In a first aspect of the invention, provided is a radio circuit comprising: a receiving circuit including at least one circuit of which linear-operating range changes in accordance with power consumption, the receiving circuit receiving radio signals and selecting a signal having a desired frequency from the received signals to demodulate the selected signal; an input-power detector for detecting power input to the receiving circuit; a received-power detector for detecting power of the signal selected by the receiving circuit; and a control circuit for controlling the receiving circuit. When the power detected by the input-power detector is larger than a first predetermined value and the power detected by the received-power detector is smaller than a second predetermined value, the control circuit increases power consumption of the circuit which is included in the receiving circuit and of which linear-operating range changes in accordance with power consumption to expand the linear operation range and thereby to make the receiving circuit operate at a low distortion.
In a second aspect of the invention, provided is a radio circuit comprising: a receiving circuit including at least one circuit of which linear-operating range changes in accordance with power consumption, the receiving circuit receiving radio signals and selecting a signal having a desired frequency from the received signals to demodulate the selected signal; an input-power detector for detecting power P
1
input to the receiving circuit; a received-power detector for detecting power P
2
of the signal selected by the receiving circuit; and a control circuit for controlling the receiving circuit. When the value of the power ratio P
2
/P
1
based on the power P
1
detected by the input-power detector and the power P
2
detected by the received-power detector is smaller than a predetermined value, the control circuit increases power consumption of the circuit which is included in the receiving circuit and of which linear-operating range changes in accordance with power consumption to expand the linear operation range and thereby to make the receiving circuit operate at a low distortion.
In the radio circuit, the receiving circuit may include a filter for selecting a signal with a specific frequency to be received. The circuit of which linear operation range changes in accordance with the power consumption may be disposed immediately before the filter.
In the radio circuit, the receiving circuit may include a gain adjustment circuit for adjusting a signal gain, and decrease the gain of the gain adjustment circuit when the power detected by a received-power detector is larger than a predetermined value to suppress power consumption of at least one of the gain adjustment circuit and circuits disposed subsequently to the gain adjustment circuit.
In the radio circuit, the receiving circuit may comprise a first path, a second path of which power consumption is large than that of the first path and of which linear operation range is wider than that of the first path, and a switch for selecting either of the first and second paths in accordance with outputs of the input-power detector and the received-power detector. The path which is not selected may be controlled to stop its operation.
In the radio circuit, the second path may include a low-noise amplifier, and the input-power detector may detect the power at a point on the output side of the low-noise amplifier.
In the radio circuit, when the receiving circuit selects and receives a desired signal out of signals in a plurality of frequency bands, any signals in the plurality of frequency bands may be received through the same circuit in the receiving circuit.
In the radio circuit, reception can be performed under transmission.
In a third aspect of the invention, provided is a method of controlling a radio circuit comprising a receiving circuit including at least one circuit of which linear-operating range changes in accordance with power consumption, the receiving circuit receiving radio signals and selecting a signal having a desired frequency from the received signals to demodulate the selected signal. The method comprises: detecting input power being input to the receiving circuit; detecting receiving power of the signal selected by the receiving circuit; and increasing power consumption of the circuit which is included in the receiving circuit and of which linear-operating range changes in accordance with power consumption to expand the linear operation range and thereby to make the receiving circuit operate at a low distortion, when the detected input power is larger than a first predetermined value and the detected receiving power is smaller than a second predetermined value.
In a fourth aspect of the invention, provided is a method of controlling a radio circuit comprising a receiving circuit including at least one circuit of which linear-operating range changes in accordance with power consumption, the receiving circuit receiving radio signals and selecting a signal having a desired frequency from the received signals to demodulate the selected signal. The method comprises: detecting input power being input to the receiving circuit; detecting receiving power of the signal selected by the receiving circuit; and increasing power consumption of the circuit which is included in the receiving circuit and of which linear-operating

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