Filters

The MAX22707 precision zero crossing detector provides a reliable and repeatable zero crossing detection signal based on an AC line input. The use of switched-capacitor filters helps to ensure minimal zero-crossing delay while tracking change in the input frequency and provides higher precision and a more inherently stable output than discrete solutions.

The MAX22707 features a low-power, precision analog filter based on the switched-capacitor technology designed for precision filtering of AC input noise. The device requires only a simple external input network preceding the AC inputs and no additional external components for the filters. The two different filter types can be selected by the Filter Selection pin (FS). The available filter types are the fourth order BPF and LPF. The DC averaging filter capacitor function is used for the latter.

The MAX22707 supports two standard line frequencies (50Hz and 60Hz) for both the filter types as well as rectified inputs in the case of LPF. If the BPF is selected, then the frequency selection Mode Control pin (MC) is used to select between 50Hz and 60Hz. If the LPF is selected, then the same pin is used to choose between 50/60Hz or 100/120Hz signal band (see Table 1). The Rectified Select pin (RS) is used to select between sine and rectified units (see Table 2). The MAX22707 is available in a compact 10-pin μMAX package and operates over the -40°C to +125°C temperature range.

Applications

• AC Phase Detection
• Flexible Zero Crossing Detection
• Industrial Lighting Dimming

The LTC6601-2 is a low power, low distortion, very easy-to-use fully differential 2nd order active broadband RC filter and driver. On-chip resistors, capacitors, and amplifier bandwidth are trimmed to provide consistent and repeatable filter characteristics.

The filter characteristics are pin-strap configurable. Cutoff frequencies range from 5MHz to 27MHz. Gain is pin-strap programmable between –17dB and +17dB.

A three-state BIAS pin is provided to adjust amplifier power consumption. Select between low power (50% power reduction), high performance and standby modes with the BIAS pin.

The LTC6601 family comes in two options which trade off distortion and noise. The LTC6601-2 offers the lowest distortion at high frequencies. The LTC6601-1 is configured for lowest noise. Both are available in pin-compatible packages.

The LTC6601-2 is available in a compact 4mm × 4mm 20-pin leadless QFN package.

Applications

• Differential A/D Converter Driver
• Antialiasing/Reconstruction Filter
• Single-Ended to Differential Conversion/Amplification
• Low Voltage, Low Noise, Differential Signal Processing
• Common Mode Voltage Translation
• Portable Instrumentation

The LTC6601-2 is a low power, low distortion, very easy-to-use fully differential 2nd order active broadband RC filter and driver. On-chip resistors, capacitors, and amplifier bandwidth are trimmed to provide consistent and repeatable filter characteristics.

The filter characteristics are pin-strap configurable. Cutoff frequencies range from 5MHz to 27MHz. Gain is pin-strap programmable between –17dB and +17dB.

A three-state BIAS pin is provided to adjust amplifier power consumption. Select between low power (50% power reduction), high performance and standby modes with the BIAS pin.

The LTC6601 family comes in two options which trade off distortion and noise. The LTC6601-2 offers the lowest distortion at high frequencies. The LTC6601-1 is configured for lowest noise. Both are available in pin-compatible packages.

The LTC6601-2 is available in a compact 4mm × 4mm 20-pin leadless QFN package.

Applications

• Differential A/D Converter Driver
• Antialiasing/Reconstruction Filter
• Single-Ended to Differential Conversion/Amplification
• Low Voltage, Low Noise, Differential Signal Processing
• Common Mode Voltage Translation
• Portable Instrumentation

The LTC6602 is a dual, matched, programmable bandpass or lowpass filter and differential driver. The selectivity of the LTC6602, combined with its phase matching and dynamic range, make it ideal for filtering in RFID systems. With two degree phase matching between channels, the LTC6602 can be used in applications requiring highly matched filters, such as transceiver I and Q channels. Gain programmability, and the fully differential inputs and outputs, simplify implementation in most systems.

Both channels of the LTC6602 consist of a programmable lowpass and highpass filter. For bandpass functionality, the lowpass filters are programmed for the upper cutoff frequency. For lowpass functionality, the highpass filters can be bypassed. The filter cutoff frequencies can be set with a guaranteed accuracy of 3% with the use of a single resistor. Alternatively, the filter cutoff frequencies can be controlled with an external clock.

The LTC6602 operates on a single 2.7V to 3.6V supply and features a low power shutdown mode.

Applications

• Multiprotocol RFID Readers: EPC-GEN2, ISD and IPX
• IDEN, PHS, GSM Basestations
• Repeaters, Radio Links, and Modems
• Wireless Telemetry
• JTRS

The LTC6603 is a dual, matched, programmable lowpass filter for communications receivers and transmitters. The selectivity of the LTC6603, combined with its linear phase, phase matching and dynamic range, make it suitable for filtering in many communications systems. With 1.5° phase matching between channels, the LTC6603 can be used in applications requiring pairs of matched filters, such as transceiver I and Q channels. Furthermore, the differential inputs and outputs provide a simple interface for most communications systems.

The sampled data filter does not require an external clock yet its cutoff frequency can be set with a single external resistor with an accuracy of 3.5% or better. The external resistor programs an internal oscillator whose frequency is divided prior to being applied to the filter networks. This allows up to three cutoff frequencies that can be obtained for each external resistor value, allowing the cutoff frequency to be programmed over a range of more than six octaves. Alternatively, the cutoff frequency can be set with an external clock. The filter gain can also be programmed to 1, 2, 4 or 16.

The LTC6603 features a low power shutdown mode that can be programmed through the serial interface and is available in a 24-pin 4mm × 4mm QFN package.

Applications

• Small/Low Cost Basestations: 
  • IDEN, PHS, TD-SCDMA, CDMA2000, WCDMA, UMTS
• Low Cost Repeaters, Radio Links, and Modems
• 802.11x Receivers
• JTRS

The LTC1564 is a new type of continuous time filter for antialiasing, reconstruction and other band-limiting applications. No other analog components or filter expertise are needed to use it. There is one analog input pin and one analog output pin. The cutoff frequency (f_C) and gain are programmable while the shape of the lowpass response is fixed. A latching digital interface stores f_C and gain settings or it can be bypassed for control directly from the pins. The LTC1564 operates from 2.7V to 10V total (single or split supplies) and comes in a 16-pin surface mount SSOP.

The LTC1564 is a rail-to-rail high resolution 8th-order lowpass filter with two stopband notches, giving approximately 100dB attenuation at 2.5 times the passband cutoff frequency f_C (a de-facto standard for DSP front ends). Signals with low or variable levels can be normalized with the built-in variable gain that reduces input-referred noise with increasing gain for a typical dynamic range (maximum signal level to minimum noise) of 122dB (20 equivalent bits) with 20kHz f_C and 118dB at 100kHz f_C on a ±5V supply.

Other frequency-response shapes can be provided upon request. Please contact Analog Devices Marketing.

Applications

• Antialias or Reconstruction Filtering
• DSP Systems
• Communications Systems
• Scientific Instruments
• High Resolutions (16 Bits to 20 Bits)
• Processing Signals Buried in Noise
• Audio Signal Processing
• Programmable Data Rates
• Automatic Gain Control (AGC)
• Single Part Replacing Multiple Filters