LTC1064-4CJ

Overview

The LTC1064-4CJ is an obsolete 8th-order, clock-sweepable Cauer lowpass switched-capacitor filter housed in a 14-pin CERDIP package. It operates on dual power supplies ranging from ±2.37V to ±8V with a maximum total supply voltage of 16.5V. The device supports cutoff frequencies up to 100kHz using a 50:1 fCLK to fCUTOFF ratio, or up to 50kHz using a 100:1 transitional Butterworth-Cauer response. Key electrical specifications include a wideband noise of 135µVRMS at ±7.5V and a total harmonic distortion of 0.03% at 3VRMS input. The operating temperature range for the 'C' suffix is -40°C to +85°C.

Feature Summary

• Provides high-selectivity filtering through an 8th-order Cauer lowpass response with minimal passband ripple.
• Features low noise and low harmonic distortion performance that competes with discrete operational amplifier active realizations.
• Allows flexible frequency programming via external TTL or CMOS clocks without requiring internal precision components.

Applications

• Antialiasing filters
• Telecom filters
• Sinewave generators

Procurement Notes

Verify component authenticity carefully as this specific part number represents an obsolete package configuration. Confirm that the 14-lead CERDIP form factor remains compatible with existing board layouts before procurement. Ensure that any replacement strategy accounts for the discontinuation status by consulting current Analog Devices inventory for alternative sourcing options.

Selection Notes

Select this component when a high-order analog filter response is required within a compact footprint. The external clock capability allows for precise tuning of the cutoff frequency relative to system timing references. Consider the transition between Cauer and Transitional modes based on the specific stopband attenuation requirements and delay linearity needs of the application design.

Part Context

This device belongs to the LTC1064 family of low-noise, high-frequency switched-capacitor filters. It shares pin compatibility with the LTC1064-1, LTC1064-2, and LTC1064-3 variants, which offer different filter responses such as Elliptic, Butterworth, and Linear Phase. The 'CJ' designation specifically identifies the ceramic dual in-line package variant manufactured using the enhanced LTCMOS silicon gate process.

Replacement Considerations

The datasheet explicitly lists the J Package as obsolete and recommends considering the N14 Package (PDIP) as an alternate source. Verify mechanical fitment if transitioning to the plastic DIP version.

FAQ

How does Pin 10 configuration affect the filter response?

Connecting Pin 10 to V+ establishes a 50:1 fCLK to fCUTOFF ratio for a Cauer response. Connecting Pin 10 to V– establishes a 100:1 fCLK to f–3dB ratio for a transitional Butterworth-Cauer response with lower noise and delay nonlinearity.

What compensation is required for cutoff frequencies above 20kHz?

To achieve minimum passband ripple and cutoff frequencies above 20kHz, compensating components must be connected to the COMP1 and COMP2 pins. Specific values are required to maintain the ±0.1dB ripple specification at higher frequencies.

How can output clock feedthrough be minimized?

Bypassing Pin 10 with a 0.1µF capacitor reduces clock feedthrough. Additionally, buffering the output with a simple RC lowpass filter having a cutoff frequency of fCLK/3 can eliminate residual clock feedthrough artifacts.