it Gb/s NRZ Modulator Driver VD1 VCTRL1 OUT/VD2 Description Features Device Diagram Gain

Transcription

1 Description The it65 is a high-performance NRZ modulator driver for metro and long-haul LiNbO optical transmitters. The device consists of a wideband iterra phemt amplifier in a surface-mount package. This component is typically used to amplify the data signal between the transmitter s MUX and an optical modulator. Its wide output amplitude range allows the it65 to properly drive either electro-absorption (EA) or Mach- Zehnder modulators. For system designers requiring a fully functional driver solution the it65 includes essential features such as MSA-compatible supply voltages, low power dissipation, medium gain, low jitter degradation, and the ability to precisely set the output amplitude and eye cross point. Additional external components are required for proper operation such as input and output coupling capacitors, bias choke network, and control circuitry to adjust the output amplitude and cross point. For lower voltage applications, the it65 provides positive bias with an on-chip resistor, which avoids the need for a bias tee or external choke network. The it65 is RoHS compliant and backward compatible with SnPb soldering. Features Device Diagram Optimized for NRZ bit rates up to.5 Gb/s Inverting polarity Low RMS jitter degradation 5 ps typical 0% - 80% transition times Adjustable output amplitude Adjustable eye cross point Power dissipation: 700 mw typ. at 6 output amplitude MSA compatible supply voltages Small form factor: 0.50 x 0.50 x in. CTRL D IN Gain OUT/D G

2 Absolute Maximum Ratings Parameter Symbol Min Max Units Operation at or beyond the maximum ratings may cause damage to this product or lead to reduced reliability. Combinations of drain voltage, drain current, and output power shall not exceed PD at package base temperature of 85 o C. Drain voltage Gate voltage Control voltage Drain current Id for low voltage applications ( D ) Id for high voltage applications ( D ) Input voltage D, G CTRL I D I D IN -.5 D ma ma p-p,. Set G such that drain currents are below maximum limits.. See Note on Pg. 9 for package thermal. impedance. Power dissipation Junction operating temperature Mounting temperature P D T J T M W o C o C 5. The peak-peak voltage variation of AC coupled signal applied to RF input. Storage temperature T STO o C 5. See application note, AN. Recommended Operating Conditions. The drain voltage applied to the device will determine the maximum available output amplitude. This voltage range is typical for a modulator driver application. Parameter Drain voltage Drain current Id for low voltage applications ( D ) Id for high voltage applications ( D ) Gate voltage Control voltage Symbol D, I D I D G CTRL Min Max Units ma ma. Operating drain currents are set using G. Base operating temperature. T BASE 0 85 o C. G may be used to adjust the output eye cross point.. CTRL should be used for output amplitude control.

3 Electrical Characteristics At 5 o C. The low frequency cutoff is determined by the component values of the external coupling capacitors and the external choke network.. Based on measured S- parameters.. Output eye cross point may be adjusted using G. Achievable cross point limits are influenced by the input signal amplitude and the specific gate used for cross point adjustment. Minimum input amplitude of.5 is required to achieve this cross point range in a driver application.. Measured between 0% and 80% of the transition. 5. In a large-signal application, this is the minimum input amplitude required to achieve an output amplitude of 6 and time domain performance suitable for a modulator driver application. 6. In a small signal application, the it65 will function as a linear gain block per the small signal parameters listed above. Parameter Polarity Bit rate High frequency small signal -db frequency Small signal gain (5 GHz) Input match 00 MHz 0 GHz 0 GHz 5 GHz Output match 00 MHz 0 GHz 0 GHz 5 GHz Input amplitude range Output amplitude range (oltage control by means of CTRL) Output cross point range Output transition time RMS jitter degradation Power dissipation at OUT = 6 Symbol F B F HIGH S S S IN OUT CP T RISE/FALL J DEG P D Min Jitter degradation is defined by the following formula: J DEG 0 Typ Max Unit Gb/s GHz (Measured Output RMS Jitter) (Measured Input RMS Jitter) db db db % ps ps W Inverting NRZ format Note Note Note 5, 6 DD = D DD = D Note Note Note 7

4 Typical Electrical Performance Ambient temp. = 5 o C D = 5.0 ID, G, and CTRL adjusted to achieve target parameter. CTRL () it65 Output Amplitude vs. CTRL Output Amplitude () it65 Power Consumption vs. Output Amplitude Device configured as shown in application schematic (page 7) Power (W) Output Amplitude () it65 RMS Jitter Degradation vs. Output oltage Jdeg (ps) Output Amplitude () it65 Transition Time vs. Output Amplitude 0.0 0% - 80% Transition Time (ps) Rise Time.0 Fall Time Output Amplitude ()

5 Typical Electrical Performance Ambient temp. = 5 o C D = 5.0 ID, G, and CTRL adjusted to achieve target parameter. in=.5 pp Bit Rate = 0.7 Gb/s Output amplitude 6 Output amplitude 5 Device configured as shown in application schematic (page 7) Output amplitude Output amplitude Input Signal =.5 pp 5

6 Typical Electrical Performance Ambient temp. = 5 o C D = 5.0 ID, G, and CTRL only were adjusted initially to achieve out = 6 at in =.5 (middle eye pattern), then varied in from to (top and bottom eye patterns). in =, out = 5. pp Bit rate = 0.7 Gb/s Device configured as shown in application schematic (page 7) in =.5, out = 6 pp in =, out = 6. pp 6

7 Application Schematic Typical configuration when using the it65 in a modulator driver application. CTRL C D C IN C Gain OUT / D (Bias tee/choke) C G Reference Designation Description Manufacturer Part Number C 0.0 µf cap, 00, X5R, 0 Panasonic ECJ-0EBA0K C C.00 µf cap, 060, X5R, 6 Panasonic ECJ-BC05K This application circuit is used on the it65 evaluation board, which is available to customers who desire a convenient test platform for this product. The it65 design was verified with the components and configuration described above. C is coupling capacitors for the RF input and output. High-performance capacitors (such as those manufactured by Presidio) may be substituted. C C are power supply decoupling capacitors. External bias tee is required at the output to provide D bias. 7

8 Package Dimensions A :. Tolerances on package length and width are ± in.. Tolerance on package height is ± in it65 xxxxx Tolerances on all pad dimensions and features are ± 0.00 in. A Substrate material: RO00, in.- thick, ½ oz. copper. Pin indicator Plating: 00 to 50 µin nickel, 5 to 0 µin. flash gold finish Package footprint available in DXF format. Contact iterra Communications for details Pin 7. RoHS Compliant. Backward compatible with SnPb soldering Typ. iew A - A Note: All dimensions are in inches. 8

9 Pad Details Pad Function Width Height Pad Function Width Height G 9 D 0 5 CTRL 6 OUT/D 7 IN 7 :. Width and height dimensions indicated in the table above are in mils.. Pad is a ground pad and also the primary thermal path for the device. The application board must provide adequate thermal transfer to the base plate or heat sink.. The thermal impedance between the package base (ground pad ) and the amplifier junction (θ jb ) is about 5 C/W. 9

10 I/O Functional Description CTRL D IN Gain OUT / D G Name CTRL D D G IN OUT/D Usage This pin is used to control the amplitude of the signal at the OUT port. This pin is used to bias the it65 through its on-chip drain resistor. This pin is optional and used for low voltage applications (out = < pp). This pin is used to bias the it65 through an external choke network.this pin is used for high voltage application (out from 6 pp to pp) This pin is used to set the it65 drain current. It may also used for output eye cross point adjustment in a driver application. The input signal to the it65 is applied to this pin. Input impedance is 50 Ω. The output signal from the it65 is measured at this pin. Output impedance is 50 Ω. 0