CXA3555N Ver la hoja de datos (PDF) - Sony Semiconductor

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Fabricante

CXA3555N

All Band Tuner IC with On-chip PLL

Sony Semiconductor 

CXA3555N

Description of Analog Block Operation (See the Electrical Characteristics Measurement Circuit.)

VHF-Low oscillator circuit

• This is a completely balanced oscillator circuit. The oscillation frequency is varied by connecting an LC parallel

resonance circuit including a varicap between Pins 16 and 18 via coupled capacitance and controlling the

voltage applied to the varicap.

VHF-High oscillator circuit

• This is a completely balanced oscillator circuit. The oscillation frequency is varied by connecting an LC parallel

resonance circuit including a varicap between Pins 17 and 19 via coupled capacitance and controlling the voltage

applied to the varicap.

VHF mixer circuit

• The mixer circuit employs a double balanced mixer with little local oscillation signal leakage.

The input format is base input type, with Pin 12 grounded either directly or via a capacitor and the RF signal

input to Pin 11.

(Pin 12 can also be used to switch the IC gain according to the applied DC voltage value. When switching the

gain with Pin 12, the GC bit of the PLL data must be set to "0".)

• The RF signal is fed from the oscillator, converted to IF frequency and output from Pins 8 and 9. Pins 8 and

9 are open collectors, so external power feed is necessary. Also, connect single-tuned filters to Pins 8 and 9.

UHF oscillator circuit

• The oscillator circuit is designed so that two collector ground type Colpitts oscillators perform differential

oscillation operation via an LC resonance circuit including a varicap.

• Resonance capacitance is connected between Pins 20 and 21, Pins 21 and 22, and Pins 22 and 23, and an

LC resonance circuit including a varicap is connected between Pins 20 and 23.

UHF mixer circuit

• This circuit employs a double balanced mixer like the VHF mixer circuit.

The input format is base input type, with Pins 14 and 15 as the RF input pins. The input method can be

selected from balanced input consisting of differential input to Pins 14 and 15 or unbalanced input consisting

of grounding Pin 14 via a capacitor and input to Pin 15.

• Pins 8 and 9 are the mixer outputs. Pins 8 and 9 are open collectors, so external power feed is necessary.

Also, connect single-tuned filters to Pins 8 and 9.

IF amplifier circuit

• Pins 5 and 6 are the IF amplifier inputs, and the input impedance is approximately 1.6kΩ.

• The signals frequency converted by the mixer are output from Pins 8 and 9, and Pins 8 and 9 are connected

to Pins 5 and 6 via capacitors. (An adjacent channel trap circuit can be formed by connecting LC parallel

circuits in place of capacitors.)

• The signal amplified by the IF amplifier is output from Pin 30. The output impedance is approximately 10Ω.

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