JPH1013282A - Power-saving method for radio receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of a tertiary mutual modulation product and also to save power of a radio receiver by controlling the gain of a radio- frequency signal amplifier means, in response to the signal intensity that is higher than a prescribed level of sensitivity. SOLUTION: The output of a radio-frequency amplifier 14 is divided by a signal dividing node 16, and some of input signals are supplied to the signal paths I and Q, which are orthogonal to each other. A signal amplitude measurement circuit 34, connected to the limiting amplifiers 27 and 28, produces an output signal to show the amplitude of the received signal. The output of the circuit 34 supplies according to the requests the gain control signals to the control input 38 of the amplifier 14 and the control input 40 of a PIN diode attenuator 12 via an LPF 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement relating to a radio receiver or a receiver of a radio transceiver included in the term "radio receiver" for simplifying the description of the present specification. The present invention is particularly directed to power savings associated with portable / mobile devices, such as wireless newspapers, digital cordless and cell phones, and mobile devices powered by batteries.

[0002]

BACKGROUND OF THE INVENTION In a radio receiver, an important feature of the architecture that affects power consumption is the radio frequency part. Since the radio receiver is movable and its distance from the transmitting antenna changes, the electric field strength of the desired signal changes over a wide range. The signal-to-noise ratio changes with changes in the electric field strength. In the case of digital signal transmission systems, the quoted sensitivity is replaced by the desired RF input power to achieve a predetermined BER (Bit Error Rate) of, for example, 0.01.

[0003] Generally, radio receivers include an automatic gain control (AGC) system to avoid non-linearities in large signal conditions due to unwanted large signals. AG
C-systems typically measure the amplitude of all signals, and the result prevents overloading the mixer that could generate a third-order intermodulation product that is larger than the desired signal lost. Therefore, it is used to reduce the gain of the radio frequency amplifier under high gain conditions.

[0004]

However, generally speaking, the sensitivity is higher than required in receiving digital signals, so using an AGC system in the above manner is optimal from a power saving point of view. is not. The purpose of the present invention is
The object is to prevent the generation of third-order intermodulation products and to improve the power savings of the radio receiver.

[0005]

According to one aspect of the present invention,
A method for power saving of a wireless receiver is provided. The gain of the radio frequency stage is controlled when the signal strength exceeds a value of the sensitivity giving a certain bit error rate by a predetermined amount. A method for conserving power in a wireless receiver provided by a first aspect of the present invention comprises the steps of determining a minimum sensitivity value for a predetermined bit error rate, and determining a predetermined sensitivity value greater than the minimum sensitivity value. And providing gain control to the input of the wireless receiver in response to signal strength above the predetermined sensitivity value.

According to another aspect of the present invention, there is provided a radio receiver comprising: a means for detecting an input radio frequency signal; a radio frequency signal amplifying means connected to the detection means; Means for determining, means for setting a threshold signal strength that exceeds a minimum sensitivity value by a predetermined amount, and means for controlling the gain of the RF signal amplifying means in accordance with the determined signal strength exceeding the threshold. Consists of

[0007]

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an input digital signal that is substantially up to a specified sensitivity up to 20 dB, for example,
Having a 15 dB higher level is based on achieving a bit error rate that reaches the requirements of the specified complete system. In other words, all desired signals are, for example,
If the level above the specified sensitivity has a level higher than 15 dB, the output signal of the radio frequency amplifier is higher than the specified minimum value, so that current is consumed to amplify such a large input signal. However, if the amplitude of the input signal is smaller, the RF amplifier will provide the desired higher amplification.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings without being limited to the examples. In the drawings, identical reference numbers are used to indicate corresponding features. The zero intermediate frequency receiver shown in FIG. 1 comprises an antenna 10 connected via a pin diode attenuator 12 to a gain adjustable radio frequency amplifier 14. The output of RF amplifier 14 is separated at signal splitting node 16 and a portion of the input signal is provided to orthogonally related signal paths I and Q. More specifically, the signal part is the signal from the mixers 17, 18
Is supplied to a first input. A local oscillator 20 having a frequency substantially corresponding to the conceptual carrier frequency of the desired signal received at the antenna 10 is connected to the second input of the mixer 17 and uses a 90 ° phase shifter 22 to
8 is connected to the second input. Mixer 1 whose phase is orthogonal
The outputs of 7 and 18 are the amplifiers 23, 2 and 2 after the respective mixers.
4 is supplied. The low-pass filters 25 and 26 select a difference signal from the result of mixing at the outputs of the amplifiers 23 and 24, respectively. Limiting amplifiers 27 and 28 have inputs connected to the outputs of low-pass filters 25 and 26, respectively,
And an output connected to a demodulator 30 having an output 32.

The signal amplitude measuring circuit 34 includes the limiting amplifier 2
7, 28. Circuit 34 generates an output signal representing the amplitude of the received signal. The output of circuit 34 is
On demand, a gain control signal is applied to the control input 38 of the RF amplifier 14 and the control input 40 of the pin diode attenuator 12.
Is connected to a low-pass loop filter 36 that supplies the power to the filter.
FIG. 2 is a graph of the desired signal strength WSS plotted against the bit error rate BER, and it can be seen that the bit error rate disappears as the desired signal strength increases. According to the invention, the bit error rate BER of the receiver is specified, for example, the corresponding sensitivity PS is determined by a prior calculation, and then the safety margin M of the receiver sensitivity is determined, for example, by the specified bit error rate. 1 above the sensitivity set to give the rate BER
Designated 5 dB higher, gain control of the radio frequency amplifier 14 and / or pin diode attenuator 12 is provided to maintain this 15 dB margin, and preferably the gain of the amplifier 14 is reduced. As a result of achieving such gain control, the current consumption of the radio frequency stage of the receiver is reduced by the bit error rate B
The ER is reduced while being kept within a certain range, and third-order intermodulation distortion is prevented.

FIG. 3 is a graph showing the desired signal strength WSS with respect to the gain control voltage AGC. At a given point on the abscissa, the receiver sensitivity for a specified bit error rate BER is called PS. The 15 dB margin M appears after the gain control voltage is increased to reduce the gain of the radio frequency amplifier 14 and / or increase the attenuation provided by the pin diode attenuator 12.

[0011] Figure 4 shows a desired signal strength WSS plotted against current consumption I _s, at point M, it is seen that the current consumption with the gain control voltage increases decreases towards a minimum value. FIG. 5 is a simplified flow chart illustrating the method according to the invention. In step 42, the signal strength for a predetermined bit error rate BER is specified. In step 44, the signal strength value is preset to a predetermined higher value, for example, 15 dB above. At step 46, the transmitted signal is received and the signal strength, eg, RSSI, is measured. In step 48, the measured signal strength RSSI is 15d
It is checked whether the value of B is exceeded. If the result of the test is negative (N), the process returns to step 46. Conversely, if the result of the test is affirmative (Y), step 5
At zero, the gain of the RF amplifier 14 and / or the attenuation of the pin diode attenuator is adjusted. The process of the above flowchart returns to step 46 until the process is terminated as shown in step 52.

Although the zero intermediate frequency amplifier has been described with reference to FIG. 1, it should be understood that the present invention also applies to superheterodyne receivers. From reading the present disclosure, other modifications will be apparent to persons skilled in the art. Such modifications have already resulted in the design of the radio receiver and its components,
It is known in the field of manufacture and use, and may be used in place of or in addition to the features described in the above disclosure of the present invention. Although the claims of the present application are formalized in specific combinations of features, the disclosure of the present application may or may not relate to the same invention described in the present claims, In addition, regardless of whether to solve the same technical problem as the present invention, a new feature explicitly or implicitly disclosed, or a combination of new features,
Alternatively, it is necessary to understand that they include their general forms. It should be noted that the applicant may formulate new claims into the above features and / or combinations of the above features during the pendency of the present application or further applications derived therefrom.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a zero intermediate frequency receiver.

FIG. 2 is a diagram illustrating a curve of WSS (desired signal strength) versus BER (bit error rate).

FIG. 3 illustrates a curve of desired signal strength versus AGC (Automatic Gain Control) voltage.

FIG. 4 shows a curve of desired signal strength versus current consumption.

FIG. 5 is a flowchart of an automatic gain control process.

[Explanation of symbols]

 Reference Signs List 10 antenna 12 pin diode attenuator 14 radio frequency amplifier 16 signal division node 17, 18 mixer 20 local oscillator 22 phase shifter 23, 24 amplifier 25, 26 low-pass filter 27, 28 limiting amplifier 30 demodulator 32 output 34 signal amplitude measurement circuit 36 Low-pass loop filter 38, 40 Control input

Claims (10)

[Claims] 1. A method for conserving power in a radio receiver in which the gain of a radio frequency stage is controlled when the signal strength exceeds a value of the sensitivity giving a certain bit error rate by a predetermined amount. Determining a minimum sensitivity value for a predetermined bit error rate; setting a predetermined sensitivity value greater than the minimum sensitivity value; and responding to a signal strength exceeding the predetermined sensitivity value. Supplying gain control to the input stage of the wireless receiver. 3. The method of claim 2, wherein said predetermined sensitivity value is set to a value substantially up to 20 dB greater than said minimum sensitivity value. 4. The method of claim 2, wherein said predetermined sensitivity value is set to a value substantially 15 dB greater than said minimum sensitivity value. 5. A means for detecting an input radio frequency signal, a radio frequency signal amplifying means connected to the detection means, a means for determining the strength of the input radio frequency signal, and a minimum sensitivity to a predetermined bit error rate A radio receiver comprising: means for setting a threshold signal strength value that exceeds a value by a predetermined amount; and means for controlling a gain of the radio frequency amplification means in accordance with the determined signal strength exceeding the threshold. 6. The receiver according to claim 5, wherein the threshold signal strength value is set to a value substantially up to 20 dB larger than the minimum sensitivity value. 7. The receiver according to claim 5, wherein the threshold signal strength value is set substantially 15 dB above the minimum sensitivity value. 8. The receiver according to claim 5, wherein said amplitude limiting means is connected to a signal input of said radio frequency signal amplifying means. 9. The receiving apparatus according to claim 5, wherein a variable signal attenuating means is connected to an input of said radio frequency amplifying means, and a degree of attenuation of said variable signal attenuating means is determined by said gain control means. vessel. 10. The receiver according to claim 9, wherein said variable signal attenuating means comprises a pin diode.