JP2000013190A - Matching circuit automatic adjusting device for receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a matching circuit automatic adjusting device which can always automatically adjust the matching circuit of a receiver in optimum and adjusts the reception sensitivity of the receiver to the maximum. SOLUTION: A variable capacitor diode 4 is installed in a matching circuit 3. Output with an adjusted matching state is monitored in RSSi 8 and a CPU controller 9 controls the follow-up of a control voltage circuit 5 so that a level measuring value becomes maximum. CPU 9 is provided with a table of variable capacitor diode control voltages against a channel. Control voltage corresponding to a reception channel is set by using the table. CPU 9 stores the level measurement value of RSSi 8 at control voltage which is set in the register. The level measurement value of RSSi 8 when control voltage is raised (or dropped) by one bit or several bits is compared with a register storage value. When the level measurement value is large, it is stored in the register and voltage control is repeated again. When the level measurement value is smaller as a result, follow-up for holding a state where control voltage is dropped (raised) by one bit is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for automatically adjusting a matching circuit of a receiver.

[0002]

2. Description of the Related Art A matching circuit of a receiver selects a receiving channel of the receiver by an L and C tuning circuit.
The conventional circuit configuration consists of fixed chip components.
A device that uses a trimmer adjustment component to match only a certain frequency band during manufacturing. A control voltage is preset for each channel using a varicap diode, and is switched. For a receiver having a wide reception band, a system in which circuits in two frequency bands are used has been proposed.

[0003]

However, in the above-mentioned method, adjustment after mounting is impossible, and variations in components are directly reflected in variations in matching, and changes in impedance due to differences in receiving channels are also affected. It is reflected similarly. In the above method, adjustment after mounting is possible, but adjustment after reaching the end user is not possible.If the reception band is wide, the change in impedance due to the difference of the receiving channel may cause the mismatch. Become. In the method described above, even if the adjustment can be performed by switching the set voltage, it cannot cope with a change in impedance due to temperature or a change in temporal characteristics of peripheral components. In another method, a receiver having a wide reception bandwidth may have to use two LNAs (Low Noise Amp). There are drawbacks.

[0004] It is an object of the present invention to provide a matching circuit that does not cope with a change in impedance due to a difference in receiving channels, a matching circuit that does not cope with changes in temperature and surrounding components over time. Solves the problem that a circuit does not support, and a receiver with a wide reception band may not be able to respond with one circuit, and automatically adjusts the matching circuit automatically and optimally to maximize the receiving sensitivity of the receiver In providing the equipment.

[0005]

An object of the present invention is to provide a receiving signal matching circuit provided with a varicap diode and monitoring the output of the matching circuit by an RSSI (Receiving Signal).
(Strength Indicator) and a controller for adjusting the applied voltage of the varicap diode so that the monitor level of the RSSI is always maximized.

[0006] The above object is also achieved by the above-mentioned controller,
This is achieved by having a table of channel to varicap diode control voltages and monitoring the vicinity of the control voltage corresponding to the table.

According to the above means, the controller monitors the RSSI while controlling and adjusting the voltage of the varicap diode, applies a voltage at which the output level of the RSSI becomes maximum to the varicap diode, and adjusts the matching circuit to the optimum matching state. To hold.

The controller has a table of control voltages of the channel-to-varicap diode and monitors the vicinity of the control voltage corresponding to the table using the table to quickly find an optimum value. Operate.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of an embodiment of the present invention. The receiver converts the radio wave received from antenna 1 to LNA
(Low Noise Amp) and the matching circuit 3 performs selective tuning of the reception channel. The matching circuit 3 is provided with a varicap diode 4 whose capacity varies according to the applied voltage.
By this variable control, the tuning frequency is matched to the channel of the received radio wave. The reception frequency matched by the matching circuit is
Is mixed with the local oscillation frequency, converted into an intermediate frequency, and further amplified by the intermediate frequency amplifier 7. The amplified output of the intermediate frequency amplifier 7 is monitored by the RSSI 8, and the CPU controller 9 controls the tracking of the control voltage circuit 5 of the varicap diode 4 so that the monitored output is always maximized.

The CPU 9 stores software and data for controlling each unit in a memory such as a ROM or a RAM, and also stores RSSI at a frequency of several points in advance.
8 sets the varicap diode control voltage at which the measured value becomes the maximum, creates a table of the reception channel pair control voltage that can be predicted from the varicap diode control voltage, and stores and stores it in the memory, and uses the control voltage corresponding to the table. The control is performed, and control is performed so as to find the optimum value by monitoring the vicinity of the control voltage.

FIG. 2 and FIG. 3 are flowcharts when the CPU 9 operates. When the power is turned on (S1), an operation is performed to control the control voltage circuit 5 with the center value of the control voltage table (S2). When a desired reception channel signal is input from the input unit, the CPU 9 judges this, reads out the voltage data corresponding to the reception channel from the control voltage table stored and held in the memory, and outputs the corresponding data to the control voltage circuit 5 from the output unit. Then, the varicap diode 4 is controlled (S6).

The matching circuit 3 is adjusted to match the reception channel by controlling the voltage of the varicap diode 4, and the matching state at that time is monitored by the RSSI 8.
The measured level of the RSSI 8 is stored in a register of the CPU 9 (S7).

Next, the CPU 9 outputs data to the control voltage circuit 5 so as to increase the control voltage by one bit, and adjusts the matching circuit 3 (S8). The measured value of RSSI8 at that time is compared with the data value stored in the register (S9). If the measured value is larger than the stored value, the measured level of RSSI8 is stored in the register (S10), and flag 1 is set (S10).
11). Further, returning to step (S8), the control voltage is again set to 1
The measured value of RSSI 8 is compared with the value stored in the register (S9). If the measured value is large, it is stored in the register (S10), and the control voltage is increased by one bit (S9).
8). This control loop is repeated to determine the optimum value of the matching circuit 3.

In the comparison of step (S9), RSS
If the measured value of I8 is smaller than the value stored in the register, the process proceeds to step (S12), and if the flag is 1, the flag is set to 0.
And outputs data in which the control voltage is reduced by one bit to control the control voltage circuit 5 and maintain the state (S1).
3). If the flag is not 1 in step (12), the control voltage circuit 5 is controlled by outputting data obtained by lowering the control voltage by 2 bits (S14).

Further, the level measured value of the RSSI 8 is compared with the value stored in the register (S15). If the measured value is smaller than the stored value, the flag is set to 0, and the control voltage is increased by one bit to output the control voltage circuit 5, thereby controlling the control voltage circuit 5. And keep that state (S
16). If the measured value is larger than the stored value, the measured value is stored in the register (S17) and the control voltage is reduced by one bit (S18).

Further, the measured level value of the RSSI 8 is compared with the value stored in the register (S19). If the measured value is larger than the stored value, the process returns to step (S17) to store the measured value in the register. If the measured value is smaller than the stored value by the comparison, the flag is set to 0, the control voltage is increased by one bit, data is output, the control voltage circuit 5 is controlled, and the state is maintained (2).
0).

The CPU 9 follows the above flow.
Operates, outputs data and controls the control voltage circuit 5, controls the varicap diode 4, and adjusts the matching circuit 3 to match the reception channel. The matching state of the matching circuit 3 is monitored by the RSSI 8, and control is performed such that the measured value is always maximum. By continuously applying the control voltage at which the measured value level of the RSSI 8 is maximized to the varicap diode 4, the matching circuit 3 can maintain an optimum matching state, and can select and receive a reception channel with high sensitivity.

When the receiving channel is changed (S
5) starts from step (S6). Also, when monitoring other channels, the CPU 9 repeats the operation in accordance with the flow shown in FIGS.

The optimum reception monitor prepares a channel-to-control voltage table in advance and finds an optimum value by monitoring a control voltage corresponding to the table when the channel is changed. Can be quick.

Further, the RSSI is monitored, the control voltage is temporarily fixed at the point where the RSSI becomes maximum, and when the receiving channel is changed or another channel is monitored, the temperature of the receiver changes for a certain period of time. At every interval (estimated by the configuration of the transceiver), the control voltage is adjusted while monitoring the RSSI again.

[0022]

As described above, according to the present invention,
It is possible to improve receiver sensitivity degradation caused by mismatch due to component variation. Further, it is possible to improve receiver sensitivity degradation caused by mismatch due to a change in a channel to be received. It is possible to improve receiver sensitivity deterioration caused by mismatch due to temperature change or deterioration of temporal characteristics of peripheral components. Further, even a receiver having a wide reception band can be handled by one circuit.

Also, the receiving sensitivity greatly depends not only on impedance matching but also on NF (Noise Figure), and in the actual design stage, it is troublesome to determine the constant of each component while adjusting both. According to the present invention, the adjustment can be performed while monitoring the RSSI directly connected to the reception sensitivity, thereby simplifying the operation.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of an embodiment of the present invention.

FIG. 2 is a flowchart at the time of operation of an embodiment of the present invention.

FIG. 3 is a flowchart at the time of operation of an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Antenna, 2 ... LNA, 3 ... matching circuit, 4 ... Varicap diode, 5 ... Control voltage circuit, 6 ... Mixer, 7
... IF amplifier, 8 ... RSSI, 9 ... Controller (CP
U).

Claims (2)

[Claims] 1. An apparatus for automatically adjusting a matching circuit of a receiver, wherein a varicap diode is provided in a matching circuit of a received signal, and an RSSI for monitoring an output of the matching circuit is provided.
And a controller for adjusting a control voltage applied to the varicap diode so that the measured level of the RSSI is always maximized. 2. The receiver according to claim 1, wherein said controller is provided with a channel-to-varicap diode control voltage table in advance, and monitors the vicinity of the control voltage corresponding to the table. Automatic matching circuit adjustment device.