The Guzik MR-5L read amplifier is designed to work with the high-impedance TMR heads. The impedance of such heads can be as high as 1000Ohm, so it is impossible to achieve a high bandwidth with a high-impedance amplifier. This is the reason, why MR-5L is a current-sense low-impedance amplifier with voltage bias. The MR-5L also incorporates a heater driver and supports connection to a microactuator on a head suspension in order to perform the mechanical and electrical tests of the microactuator. The Guzik high-impedance injector (passive or active) is recommended for the calibration or the performance measurements of the MR-5L.

• Bandwidth from DC to 2GHz
• Writer driver 2Gbit/sec
• Head impedance from 100Ohm to 1000Ohm
• Supports heater (single-ended or differential)
• Microactuator compatible

MR Amplifier 5L Specifications:

Read Amplifier

• Differential current sense low impedance amplifier
• Bandwidth: DC to 2GHz at -3dB
• Flatness: ±0.5dB, 0.3MHz to 1GHz
• Input noise: 1.0 (typical)
• TMR bias voltage: programmable ±400mV in 0.1mV steps
• TMR impedance measurements accuracy: 1% within the bias voltage range (20 mV to 400 mV)
• Common mode rejection ratio: 24dB (typical) in full bandwidth (worst 18dB at 700MHz)
• Non-linear distortions (1GHz, 1mV input level): less than 1%
• Amplification: 30dB*
• Write to read recovery time: 100nsec (typical) for both Bias On and Shut Down Bias modes**
• Input impedance: 80Ohm differential (typical)
• Guzik MR5L Head Amplifier Compatibility: with Universal Preamplifier UP8 only.

Write Driver (General Specification)***

• Write data speed: up to 2Gbit/sec
• Rise/fall time of write current: (10-90%) 300psec****
• Programmable overshoot : up to 100% of write current in 1% steps
• Output common mode voltage: less than ±0.1V
• Write current: programmable 2mA to 80mA (zero to peak) in 0.02mA steps*****
• Read to write recovery time: less than 40nsec
• Head voltage swing: more than 12V peak to peak
• Output impedance: 100Ohm differential

Heater Features:

• Single ended or differential output configurable on the board upon customer request
• Output heater voltage: from 0V to 8V (typical, adjustable upon customer request)
• Two types of heater voltage control:

  Internal: with separate control in the read and write modes by an internal DAC

  External (through MCX connector): input range from 0V to 2V, amplification 4 (typical, adjustable upon customer request), low pass filter 4MHz cut-off frequency

• Heater impedance: not less than 50Ohm.
• Rise/Fall time:

  For external control: 100nsec (defined by 4MHz low pass filter)

  For internal control: 100nsec (typical)

• Heater current and voltage measurements:

  Current measurement accuracy ±1.0mA

  Voltage measurement accuracy ±5.0mV

• Maximum output current: 125mA

* Required amplification is provided by UP8.

** Measurement conditions: write current 50mA, head inductance 20nH, and write data 1Gbit/sec.

*** MR-5L comes with Guzik Write Driver Revision 5 (for more details see the bulletin "Guzik Read/Write Amplifier Revision 5").

**** Measurement conditions: write current 50mA, 100% overshoot, and L=20nH in series with R=20Ohm; current probe Tektronix CT-6.

***** Maximum overshoot value in write current range 50-80mA should be calculated according with the formula I overshoot + I write = 100mA.

MR-5L Frequency Response

Measurement Conditions: high-impedance injector, MR-5L only (Above),
MR-5L with Guzik Universal Preamplifier 8 (Below)

MR-5L Write-to-Read Recovery Time

Measurement Conditions:

• Write data 200 Mbit/sec
• Write Current: 50mA
• High-impedance injector