KR100464903B1 - Method of testing one-chip IC for cordless telephone - Google Patents

Abstract

The present invention relates to a test method and a test apparatus for testing a single chip IC for a wireless telephone under the same operating conditions as a wireless telephone set. In the test method of a receiver of a single chip IC according to the present invention, a VCO, a receiver programmable counter, and a receiver are connected by connecting an LC oscillator circuit to a VCO external oscillator circuit connecting pin and a low pass filter connected to a VCO input pin and an output pin of a receiver phase comparator. The phase comparator and the low pass filter are configured to form a VCO loop circuit.The transmitter phase comparator test of the PLL unit is performed by connecting the LC oscillator circuit and the low pass filter between the input pin of the transmitter programmable counter and the transmitter phase comparator output pin. The test is made by applying a 1 kHz signal to the ALC input pin at 7.4 mV _rms , again at 74 mV _rms , and then at 7.4 mV _rms to measure the voltage at the ALC output pin.

Description

Test method for single chip ICs for cordless telephones {Method of testing one-chip ICs for cordless telephone}

The present invention relates to a single chip IC test for a wireless telephone. Specifically, the present invention relates to a test method and a test apparatus for testing a single chip IC for a wireless telephone under the same operating conditions as a wireless telephone set.

One chip ICs used in cordless telephones have to be inspected for each component block in the IC, resulting in quality problems due to the conditional mismatch with the cordless telephone set (hereinafter simply referred to as "set"). As a result, customers' reliability of their own products is reduced, and management losses are caused by cost increase and opportunity loss caused by continuous improvement of problems.

Before describing the conventional method of testing single-chip ICs, a brief description of a cordless phone set is provided. See FIG. 1.

Receiver: The high frequency FM signal received from the antenna ANT is amplified by the high frequency amplifier, converted into the first intermediate frequency IF by the channel frequency output from the PLL circuit in the first mixer, and then intermediate frequency amplified (IF amplified). The second mixer is converted to a second intermediate frequency of 455 kHz and IF amplified. In addition, the signal is limited to a constant amplitude in the limiter so that the amplitude modulation component due to noise is removed and then detected in the detector. The voice signal of the detector output is extended by a signal expander, and then applied to a de-emphasis circuit to reduce noise of a high frequency component to restore the original voice signal and output the speaker SP.

Transmitter: The voice signal applied from the microphone MIC is applied to the pre-emphasis via a speech network to artificially increase the signal-to-noise ratio (S / N ratio) of the high frequency component. Next, the signal compressor increases the S / N ratio of the microlevel signal to prevent distortion caused by the channel transmission characteristics, locks it to the channel frequency after frequency modulation (FM), and then amplifies the antenna by power amplification. The transmission is made from the base (fixed station of the wireless telephone) to the handset or vice versa.

In order to simplify the circuit of the radiotelephone and reduce the production cost, a single-chip IC in which a main portion of the circuit, for example, the block 100 indicated by the dotted line in FIG. 1 is integrated into one IC chip is widely used. However, before delivering these single-chip ICs to wireless phone producers, single-chip IC producers must test the ICs.

At this time, conventionally, only basic functional tests are performed on single-chip ICs separately from the characteristics of sets (wireless telephones). In other words, the operating condition of the set and the inspection condition of the single-chip IC are tested under different conditions. Referring to Figure 2, it will be described in detail for each test item.

1) Receiver characteristic test

The receiver 200 tests a method of applying a test signal to the receiver input pin 101 and measuring the same at the voice signal output pin 110 instead of testing the operating characteristics for each frequency set for each channel. It demonstrates concretely. When the 49.71MHz single signal is input to the receiver input pin 101, the signal is first controlled by a VCO (voltage controlled oscillator) 23 and a first mixer 21 using a 39.015MHz crystal. Frequency is converted to 10.695MHz. Here, the VCO 23 is a circuit serving as a local oscillator, and is oscillated by a crystal oscillator connected to the external pins 102 and 103. The first intermediate frequency is then converted into a second intermediate frequency of 455 kHz by a local oscillator (OSC) 24 and a second mixer 22 using a 10.24 MHz crystal and then filtered after being filtered by a band filter (BPF, not shown). After reconstructing the original voice signal from the detector 25 through the device (not shown), the voice amplifier 26 is outputted through the voice signal output pin 110. The rms voltage value of the audio signal is measured to evaluate the characteristics of the IC receiver 200.

However, following this test method, it is impossible to check the channel locking frequency of the PLL or the operating characteristics of the VCO, and to detect that the frequency changes as the capacitance of the capacitor connected to the 10.24 MHz local oscillator inside the IC changes. Is impossible.

2) Phase comparator output (PDT) test of transmitter

Transmitter test signal (10MHz and 60MHz) is applied to input pin 105 of transmitter programmable counter 32 of PLL unit 300 and then output from transmitter phase detector 35 output pin 107 Phase comparison signal is measured and tested. However, according to this method, it is impossible to test for each channel frequency of transmitter and to verify whether the channel frequency fluctuates (standard: 49.7MHz ± 1kHz). In addition, it is not possible to measure whether the transmitter PLL is frequency locked.

3) Input characteristic (ALC) test

To test the input characteristics of the transmitter 400, an AC signal 1kHz / 70mV _rms (DC level =) at the input level of the automatic level controller located at the input of the transmitter 400, i.e., the input pin 109 of the ALC (automatic level controller 41). 0.9 V), and measured the magnitude of the signal from the ALC output pin 108. However, in the set, the 1V reference voltage is divided by a resistor to make 0.9V voltage. In the IC manufacturing process, the reference voltage changes by ± 0.1V, so the ALC voltage actually drops to 0.81V. Therefore, the set condition cannot be satisfied in the above manner.

On the other hand, for effective inspection of a single chip IC, many signal sources are required for inspection, but it requires a lot of investment to have all of them. Therefore, conventionally, one block of signal must be sequentially examined as one signal source. (Fig. 3). Therefore, it took a lot of inspection time and was a factor which raises the product cost.

Accordingly, it is an object of the present invention to provide a method and apparatus for testing a single chip IC for a wireless telephone under the same conditions as the operating conditions of the wireless telephone set.

Another object of the present invention is to provide a method for testing each block of a single chip IC in parallel at one time.

In order to achieve the above object, the single-chip IC test method according to the present invention includes a VCO for generating a reference signal for converting a received high frequency signal into a first intermediate frequency and a received signal input pin to which a high frequency signal received from an antenna is input. External oscillator circuit connection pins, VCO input pins, and a local oscillator receiving unit including a voice signal output pin for converting the first intermediate frequency into a second intermediate frequency and recovering the voice signal at the second intermediate frequency to output the voice signal. Wow; Transmitter for dividing the input frequency The input pin of the programmable counter, the input pin of the reference signal programmable counter for generating a desired frequency from the reference signal, The transmitter for comparing the phase difference between the output frequency of the programmable counter and the output frequency of the reference signal programmable counter A PLL unit including an output pin of a phase comparator and an output pin of a receiver phase comparator for comparing a phase difference between an output frequency of the receiver programmable counter and an output frequency of a reference signal programmable counter; A method for testing an IC chip for a wireless telephone including a transmitter including an ALC input pin and an ALC output pin, wherein the receiver test connects an LC oscillation circuit to the VCO external oscillator circuit connecting pin, and connects the VCO input pin to the VCO input pin. A low pass filter is connected to an output pin of the receiver phase comparator so that the VCO, the receiver programmable counter, the receiver phase comparator, and the low pass filter form a VCO loop circuit, and a receiver test signal is applied to the receiver signal input pin. This is done by measuring the voltage of the voice signal output from the voice signal output pin.

The transmitter phase comparator test of the PLL unit comprises connecting an LC oscillator circuit and a low pass filter between an input pin of the transmitter programmable counter and a transmitter phase comparator output pin to connect the transmitter programmable counter, the transmitter phase comparator, the low pass filter, and the LC oscillator circuit. Is achieved by measuring the frequency of the input pin of the transmitter programmable counter.

The ALC test is characterized by measuring the voltage of the ALC output pin by sequentially applying a signal of 1kHz to the ALC input pin to 7.4mV _rms , again to 74mV _rms , again to 7.4mV _rms .

The single chip IC test apparatus according to the present invention includes a receiving signal input pin to which a high frequency signal received from an antenna is input, and an external oscillating circuit connecting pin of a VCO generating a reference frequency for converting the received high frequency signal into a first intermediate frequency. A receiving unit including an input signal of a VCO and a voice signal output pin which converts a first intermediate frequency into a second intermediate frequency as a local oscillator and restores a voice signal at the second intermediate frequency to output a voice signal; Transmitter for dividing the input frequency The input pin of the programmable counter, the input pin of the reference signal programmable counter for generating a desired frequency from the reference signal, The transmitter for comparing the phase difference between the output frequency of the programmable counter and the output frequency of the reference signal programmable counter A PLL unit including an output pin of a phase comparator and an output pin of a receiver phase comparator for comparing a phase difference between an output frequency of the receiver programmable counter and an output frequency of a reference signal programmable counter; An apparatus for testing an IC chip for a wireless telephone including a transmitter comprising an ALC input pin and an ALC output pin.

The receiver test apparatus includes an LC oscillator circuit connected to the VCO external oscillator circuit connection pin and a low pass filter connected to the VCO input pin and an output pin of the receiver phase comparator.

The transmitter phase comparator test apparatus of the PLL unit includes an LC oscillator circuit and a low pass filter connected between an input pin of the transmitter programmable counter and a transmitter phase comparator output pin.

The ALC test apparatus is characterized in that it comprises a signal source that sequentially generates a signal of 1kHz connected to the ALC input pin to 7.4mV _rms , again 74mV _rms , again 7.4mV _rms .

Hereinafter, preferred embodiments of the present invention will be described with reference to FIGS. 4 to 7.

1) Receiver characteristic test

As shown in Fig. 4, instead of connecting a crystal oscillator to pins 102 and 103 of the VCO 23, an LC oscillation circuit 28 consisting of L ₁ and C ₁ is connected and the loop filter 29 is input to the VCO. A VCO loop circuit was constructed between the pin 104 and the receiver phase comparator 34 and the output pin 106. The oscillation frequency of the LC oscillation circuit 28 is determined as follows.

o _osc = ₁₁

f _ch1 (33.025 MHz) = π _11vari

In the above equation, L ₁ = 0.47μH and C ₁ = 22 ~ 25pF. C ₁ was determined by considering the pattern of the circuit board and the capacitance of the on / off relay. C _i is the internal capacitance of the VCO 23 inside the IC chip, and C _var is determined by the barrier cap characteristic according to the loop filter output value due to the phase difference of the VCO loop circuit (to be described later).

A VCO loop circuit according to the present invention will be described with reference to FIG. FIG. 5 shows only a closed circuit constituted by the loop filter 29 in FIG. This VCO loop circuit is formed by a receiver programmable counter 31, a reference signal programmable counter 33, a receiver phase comparator 34, a VCO 23, and a loop filter 29. It receives the 10.24MHz crystal oscillator oscillation signal and divides it at 5kHz from the reference signal programmable counter 33 and provides this signal as a reference signal of the receiver phase comparator 34. The difference value of the phase comparator 34 is corrected by continuously rotating the loop so that the frequency division value (which is provided by the controller Micom) becomes the same frequency as the reference signal (5 kHz). The difference width appearing in the phase comparator 34 is converted into a DC voltage while passing through the loop filter 29, which is an RC low pass filter, and the capacitance C _var inside the VCO 23 is generated by a variable capacitor. The oscillation frequency of the VCO 23 is changed by changing the value.

An example of the American standard with 25 channels will be described in detail. In the case of channel 21 of 25 channels, 5.6770 kHz is input to one of the receiver phase comparators 34 from the corresponding reference signal programmable counter 33 in the 10.24 MHz reference clock, and the frequency due to the LC oscillation is the receiver programmable counter ( 31 is input to another pin of the phase comparator 34 and through the loop filter 29 to the VCO 23 until there is no phase difference between them. At this time, the DC voltage of the loop filter 29 is measured to determine whether the voltage is within 0.4 to 3.3V. Also, in case of normal product, since LC oscillation frequency is 36.075MHz, 46.770MHz is inputted to the receiver input pin 101 so that the output of the first mixer 21 is outputted at 10.695MHz, which is its difference frequency, and finally becomes a voice signal. Since it is output to the signal output pin 110 can be measured and tested.

2) PDT test

A transmitter loop filter 36 and an LC oscillation circuit 37 are formed between the PDT output, that is, between the output pin 107 of the transmitter phase comparator 35 and the input pin 105 of the transmitter programmable counter 32 as shown in FIG. It was. The principle is the same as the receiver VCO loop circuit described above. That is, the transmitter programmable counter 32, the transmitter phase comparator 35, the transmitter loop filter 36, and the LC oscillation VCO circuit 37 constitute the transmitter VCO loop circuit. The receiver VCO loop circuit 29 described above only needs to configure the loop filter 29 outside the IC 100 because the VCO 23 is inside the IC 100. However, the transmitter VCO loop circuit 37 has a VCO circuit 37 outside the IC. Was added separately. The LC oscillation circuit is formed by varactor diode D1 and inductor L2, and the oscillation frequency amplified by transistor Q1 is input to transmitter programmable counter 32 and the phase difference is matched by transmitter phase comparator 35. The transmitter loop filter 36 is circulated.

The operation of this circuit will be described in detail. When the controller (not shown) programs the data of the input pin of the transmitter programmable counter 32 according to the corresponding channel, the data is divided (for example, 1/9752), and the frequency division and the reference signal programmable counter 33 Compared with the reference frequency, the difference frequency thereof is output to the output pin 107 of the transmitter phase comparator 35 and is converted into a DC value through a loop filter 36 configured outside the IC, and this DC value is again D1 and L2. The frequency is generated by the LC oscillator circuit 37 and the signal is re-input to the input pin 105 of the transmitter programmable counter 32 until there is no phase difference between the transmitter phase comparator 35 (frequency Rotate the locked loop. For channel 1 of the American standard, this fixed frequency is 48.760 MHz.

After this configuration, input the data of the corresponding channel to the data pin (not shown) of the controller and measure the output frequency at the emitter terminal (ie pin 105) of transistor Q1 to test whether the correct frequency comes out. You can also see if the frequency is fixed.

3) Input characteristic (ALC) test

ALC input to the pin 109, the frequency of the signal similar to the speech signal to a 1kHz _rms 7.4mV, back to 74mV _rms, re-applied sequentially to 7.4mV _rms tests the operation or not. This allows you to create test conditions that are identical to the actual set of conditions.

On the other hand, instead of the sequential test for each block, which has been a problem in the prior art, according to the present invention, a parallel test is performed in which each block of the IC is examined at once (Fig. 6). In this case, you should not simply apply a single signal source to multiple blocks, but design a signal source for each block. The design conditions of the signal source required for each block are as follows.

a. Signal Compressor: Frequency = 1kHz, Amplitude = 13mV _rms , THD = 0.2% or less (THD = total harmonic distortion)

b. Signal expander: frequency = 1 kHz, amplitude = 30 mV _rms , THD = 0.2% or less

c. For each input of the signal compressor and the signal expander, level adjustment of -10 dB, -20 dB, -30 dB, and -40 dB is required.

According to the above design conditions, the circuit shown in FIG. 7 was constructed using the MC8038 device. The MC8038 is a waveform generator IC that can output sine waves, triangle waves, and square waves. Attenuation to control the output level and attenuate the level with DC voltage to achieve levels of 1 kHz, 30 mV (0 dB), 9.48 mV (-10 dB), 3.0 mV (-20 dB), and 0.9486 mV (-30 dB) required for the test. The circuit 500 is implemented on the output side. By selecting the switches S1, S2, and S3, the output waveforms of the MC8038 are 0dB (S1 S2 S3 on), -10dB (S1 off, S2 S3 on), and -20dB (S1 S2) by the resistors R9, R10, and R11, respectively. Off, S3 on), and -30dB (all S1 S2 S3 off).

As described above, according to the present invention, by applying the PLL VCO loop circuit during the receiver test, it is possible to check the channel fixed frequency of the PLL or the operating characteristics of the VCO, and the capacitance of the capacitor connected to the 10.24 MHz local oscillator inside the IC changes. As a result, it is possible to detect the change of frequency. In addition, the PLL VCO loop circuit can be applied to test the phase comparison output of the transmitter to test the channel frequency of the transmitter and verify whether the channel frequency is changed (standard: 49.7MHz ± 1kHz). In addition, the frequency locking of the transmitter PLL can be measured. It is also possible to test the ALC circuit in the same manner as the set conditions. In addition, each internal block of the IC can be tested at the same time in parallel to reduce the test time.

As a result, single-chip ICs can be tested under the same operating conditions as cordless telephone sets, improving IC productivity and lowering production costs.

1 is a block diagram of a typical wireless telephone.

Fig. 2 is a block diagram showing a conventional single chip IC test circuit for a radiotelephone.

3 is a flowchart showing a conventional sequential test method.

4 is a block diagram showing a circuit for testing a single chip IC for a radiotelephone according to the present invention.

FIG. 5 is a block diagram showing a loop circuit formed by "29" in FIG.

6 is a flowchart illustrating a parallel test method according to the present invention.

FIG. 7 is a circuit diagram showing an example of a signal source for applying to the test method shown in FIG.

<Description of Major Symbols in Drawing>

100: Single chip IC for wireless telephone 200: Receiver

300: PLL section 400: transmitting section

500: output attenuation circuit

21: first mixer 22: second mixer

23: voltage controlled oscillator (VCO)

24: oscillator (OSC)

25: Detector 26: Voice Amplifier

28: LC oscillation circuit 29: VCO loop circuit

31: Receivable programmable counter

32: transmitter programmable counter

33: reference signal programmable counter

34: receiver comparator 35: transmitter comparator

36: loop filter 37: oscillation circuit

41: automatic level controller (ALC)

42: signal compressor 43: transmitter

Claims (2)

Receiving signal input pin into which the high frequency signal received from the antenna is input, the external oscillator circuit connecting pin of the VCO generating a reference frequency for converting the received high frequency signal into the first intermediate frequency, the input pin of the VCO, and the first as a local oscillator. A receiving unit including a voice signal output pin for converting an intermediate frequency into a second intermediate frequency and restoring a voice signal at the second intermediate frequency to output a voice signal; Transmitter for dividing the input frequency The input pin of the programmable counter, the input pin of the reference signal programmable counter for generating a desired frequency from the reference signal, The transmitter for comparing the phase difference between the output frequency of the programmable counter and the output frequency of the reference signal programmable counter A PLL unit including an output pin of a phase comparator and an output pin of a receiver phase comparator for comparing a phase difference between an output frequency of the receiver programmable counter and an output frequency of a reference signal programmable counter; A method for testing an IC chip for a wireless telephone including a transmitter including an ALC input pin and an ALC output pin, The receiver test, Connect the LC oscillation circuit to the VCO external oscillator circuit connecting pin, A low pass filter is connected to the VCO input pin and the output pin of the receiver phase comparator such that the VCO, the receiver programmable counter, the receiver phase comparator, and the low pass filter form a VCO loop circuit. By applying a receiver test signal to the received signal input pin It is made by measuring the voltage of the voice signal output from the voice signal output pin, The PLL transmitter phase comparator test By connecting an LC oscillator circuit and a low pass filter between an input pin of the transmitter programmable counter and a transmitter phase comparator output pin, the transmitter programmable counter, the transmitter phase comparator, the low pass filter, and the LC oscillator circuit form a loop circuit. Measure the voltage of the input pin of the transmitter programmable counter, The ALC test A method of testing a single chip IC for a wireless telephone, comprising measuring a voltage at the ALC output pin by sequentially applying a signal of 1 kHz to an ALC input pin at 7.4 mV _rms , again at 74 mV _rms , and again at 7.4 mV _rms . Receiving signal input pin into which the high frequency signal received from the antenna is input, the external oscillator circuit connecting pin of the VCO generating a reference frequency for converting the received high frequency signal into the first intermediate frequency, the input pin of the VCO, and the first as a local oscillator. A receiving unit including a voice signal output pin for converting an intermediate frequency into a second intermediate frequency and restoring a voice signal at the second intermediate frequency to output a voice signal; Transmitter for dividing the input frequency The input pin of the programmable counter, the input pin of the reference signal programmable counter for generating a desired frequency from the reference signal, The transmitter for comparing the phase difference between the output frequency of the programmable counter and the output frequency of the reference signal programmable counter A PLL unit including an output pin of a phase comparator and an output pin of a receiver phase comparator for comparing a phase difference between an output frequency of the receiver programmable counter and an output frequency of a reference signal programmable counter; An apparatus for testing an IC chip for a wireless telephone including a transmitter comprising an ALC input pin and an ALC output pin. The receiver test device, LC oscillation circuit connected to the VCO external oscillation circuit connection pin, A low pass filter connected to the VCO input pin and an output pin of the receiver phase comparator; Transmitter phase comparator test apparatus of the PLL unit An LC oscillator circuit and a low pass filter connected between an input pin of the transmitter programmable counter and a transmitter phase comparator output pin; The ALC test apparatus A 1-chip IC test apparatus for a radiotelephone comprising a signal source sequentially generating a signal of 1 kHz connected to an ALC input pin at 7.4 mV _rms , again at 74 mV _rms , and again at 7.4 mV _rms .