Semiconductor integrated circuit device and test method therefor
View Patent ↗During testing frequency divider PS, test control voltage signal TC and RF test signal TS are supplied via balun Ti to input terminals IN 1 and IN 2 . Test control voltage signal TC flows through resistors R 1 , R 2 to turn on NPN transistor Q 0 . A current from current source I 1 then ceases to be supplied through voltage-controlled oscillator V 1 and buffer B 10 to voltage-controlled oscillator V 1 and buffer B 10 to halt their operation. Output impedance of buffer B 10 is increased. Since potential of input terminals is that of test control voltage signal TC, varactor diodes VD 1 , VD 2 are forward-biased, increasing capacitance values of the varactor diodes further. RF test signal TS may be supplied to frequency divider PS, through varactor diodes VD 1 , VD 2 , without being affected by buffer B 10 exhibiting high output impedance. Chip area of test circuit for PLL circuit is reduced.
1. A semiconductor integrated circuit device comprising:
a phase locked loop; said phase locked loop including a phase comparator that compares a phase of a reference signal with a phase of an output signal of a frequency divider to detect phase difference therebetween, a voltage controlled oscillator that generates an oscillation signal controlled to render said phase difference constant, and said frequency divider that divides the frequency of said oscillation signal to output the resulting frequency divided signal to said phase comparator;
said semiconductor integrated circuit device further comprising:
a test signal input terminal device;
a capacitive device connected between said test signal input terminal device and an input end of said frequency divider; and
a control circuit connected to said test signal input terminal device; said control circuit exercising control so that, when a d.c. voltage is applied to said test signal input terminal device, a buffer circuit, connected to an output side of said voltage controlled oscillator, will not be in operations,
wherein said capacitive device comprises a varactor diode arrangement.
2. The semiconductor integrated circuit device according to claim 1 , wherein said varactor diode arrangement is reverse-biased and forward-biased during normal operation and during testing of said PLL circuit, respectively.
3. The semiconductor integrated circuit device according to claim 1 , wherein said test signal input terminal device is formed of two input terminals receiving a non-inverting test signal and an inverting test signal;
said varactor diode arrangement comprises two varactor diodes connected to said two input terminals; and
said non-inverting test signal and the inverting test signal, supplied to said input terminals, are supplied to said frequency divider.
4. The semiconductor integrated circuit device according to claim 1 , wherein said control circuit exercises control to halt supply of the power supply current to said voltage controlled oscillator and to said buffer circuit when said d.c. voltage is supplied to said test signal input terminal device.
5. A test method for a semiconductor integrated circuit device comprising:
providing a semiconductor integrated circuit device comprising:
a phase locked loop circuit; said phase locked loop circuit including: a phase comparator that compares a phase of a reference signal with a phase of an output signal of a frequency divider to detect phase difference therebetween, a voltage controlled oscillator that generates an oscillation signal controlled to render said phase difference constant, and said frequency divider that divides the frequency of said oscillation signal to output the resulting frequency divided signal to said phase comparator; said semiconductor integrated circuit device further comprising:
a test signal input terminal device;
a capacitive device connected between said test signal input terminal device and an input end of said frequency divider; and
a control circuit connected to said test signal input terminal device; said control circuit exercising control so that, when a d.c. voltage is applied to said test signal input terminal device, a buffer circuit, connected to an output side of said voltage controlled oscillator, will not be in operation;
said method further comprising:
applying said d.c. voltage and a test signal for said frequency divider to said test signal input terminal device to test said frequency divider
wherein said test signal input terminal device comprises two input terminals receiving a non-inverting test signal and an inverting test signal;
said capacitive device comprises two varactor diodes connected to said two input terminals so that said varactor diodes are reverse-biased during the normal operation and forward-biased during testing of said PLL circuit: and
said non-inverting test signal and said inverting test signal are supplied to said two input terminals.
6. The test method for testing a semiconductor integrated circuit device according to claim 5 , wherein
said d.c. voltage and the test signal for said frequency divider are supplied to said two input terminals via a balun.
7. A semiconductor integrated circuit device comprising:
a phase locked loop; said phase locked loop including a phase comparator that compares a phase of a reference signal with a phase of an output signal of a frequency divider to detect phase difference therebetween, a voltage controlled oscillator that generates an oscillation signal controlled to render said phase difference constant, and said frequency divider that divides the frequency of said oscillation signal to output the resulting frequency divided signal to said phase comparator;
said semiconductor integrated circuit device fUrther comprising:
a test signal input terminal device;
a capacitive device connected between said test signal input terminal device and an input end of said frequency divider; and
a control circuit connected to said test signal input terminal device; said control circuit exercising control so that, when a d.c. voltage is applied to said test signal input terminal device, a buffer circuit, connected to an output side of said voltage controlled oscillator, will not be in operation,
wherein said control circuit comprises a resistance which is connected to a test signal input terminal device and a transistor whose base is connected to said resistance, and whose collector is connected to said voltage controlled oscillator.
8. The semiconductor integrated circuit according to claim 7 , wherein the capacitive device comprises a varactor diode arrangement.
9. The semiconductor integrated circuit device according to claim 8 , wherein said varactor diode arrangement is reverse-biased and forward-biased during normal operation and during testing of said PLL circuit, respectively.
10. The semiconductor integrated circuit device according to claim 8 , wherein said test signal input terminal device is formed of two input terminals receiving a non-inverting test signal and an inverting test signal;
said varactor diode arrangement comprises two varactor diodes connected to said two input terminals; and
said non-inverting test signal and the inverting test signal, supplied to said input terminals, are supplied to said frequency divider.
11. The semiconductor integrated circuit device according to claim 8 , wherein said control circuit exercises control to halt supply of the power supply current to said voltage controlled oscillator and to said buffer circuit when said d.c. voltage is supplied to said test signal input terminal device.