QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1524A-A 200MHZ TO 6000MHZ QUADRATURE MODULATOR WITH ULTRAHIGH OIP3 LTC5588-1 DESCRIPTION Demonstration circuit 1524A-A is a high linearity direct drives a precision quadrature phase shifter followed by quadrature modulator featuring the LTC 5588-1. LO buffers, which in-turn drive the upconverting mix- ers. The LTC5588-1 is a direct conversion I/Q modulator designed for high performance wireless applications. It The LTC5588-1 offers exceptional linearity performance. allows direct modulation of an RF signal using differen- An external voltage can be applied to the LINOPT pin to tial baseband I and Q signals. It supports LTE, GSM, further improve its output 3rd-order intercept. The EDGE, TD-SCDMA, CDMA, CDMA2000, W-CDMA, Wi- LTC5588-1s supply voltage range is 3.15V to 3.45V, Max and other communication standards. It can also be and consumes about 303mA current. configured as an image reject upconverting mixer, by Demonstration circuit 1524A-A is designed for evaluat- applying 90 phase-shifted signals to the I and Q inputs. ing the LTC5588-1 IC at RF frequencies from 700MHz The LTC5588-1 accepts externally applied balanced I to 5GHz. With a few component changes, it can be eas- and Q baseband input signals with a common-mode ily optimized for evaluations at lower or higher frequen- voltage level of 0.5V. These voltage signals are con- cies. Refer to Application Note section and the verted to currents and translated to RF frequency by LTC5588-1 data sheet for details. means of double-balanced upconverting mixers. The Design files for this circuit board are available. Call mixer outputs are combined to single-ended through an the LTC factory. on-chip RF output balun, which also transforms the , LT, LTC, and LTM are registered trademarks of Linear Technology Corp. output impedance to 50 for a wide RF frequency All other trademarks are the property of their respective owners. range. A single-ended or differential LO input signal Table 1. Typical Demo Circuit Performance Summary T = 25C V = 3.3V, EN = 3.3V BBPI, BBMI, BBPQ, BBMQ common-mode DC Voltage V = 0.5V , I and Q baseband input signal = 100kHz CW, A CC CMBB DC 1V each (two-tone I and Q baseband input signal are at 4.5MHz and 5.5MHz), I and Q 90 shifted, lower side-band selection P = 0dBm f = P-P(DIFF) LOM RF f f , unless otherwise noted. LO BB PARAMETER CONDITIONS TYPICAL PERFORMANCE Supply Voltage 3.15V to 3.45V Supply Current I +I , EN = High 303mA CC1 CC2 Sleep Current I +I , EN = 0V 33A CC1 CC2 Baseband Bandwidth -1dB Bandwidth, R = 25, Single-ended 430MHz SOURCE Baseband Input Current Single-Ended -136A Baseband Input Resistance Single-Ended -3k Baseband DC Common-Mode Voltage Externally Applied 0.5V Baseband Amplitude Swing No Hard Clipping, Single-Ended 0.86V P-P LO Match Frequency Range Standard Demo Board, S < -10dB 600MHz to 6000MHz 11 RF Match Frequency Range Standard Demo Board, S < -10dB 700MHz to 5000MHz 22 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1524A-A 200MHZ TO 6000MHZ QUADRATURE MODULATOR WITH ULTRAHIGH OIP3 T = 25C V = 3.3V, EN = 3.3V BBPI, BBMI, BBPQ, BBMQ common-mode DC Voltage V = 0.5V , I and Q baseband input signal = 100kHz CW, A CC CMBB DC 1V each (two-tone I and Q baseband input signal are at 4.5MHz and 5.5MHz), I and Q 90 shifted, lower side-band selection P = 0dBm f = P-P(DIFF) LOM RF f f LINOPT pin floating unless otherwise noted. LO BB PARAMETER CONDITIONS TYPICAL PERFORMANCE f = 900MHz f = 1900MHz f = 2140MHz f = 2600MHz LO LO LO LO Conversion Voltage Gain 20 Log (V / V ) 0dB 0.4dB 0.2dB -0.2dB RF(OUT)(50) IN(DIFF)(I OR Q) Absolute Output Power 1V CW Signal, I and Q 4.0dBm 4.4dBm 4.2dBm 3.8dBm P-P(DIFF) Output 1dB Compression 12.1dBm 12.4dBm 12.0dBm 11.4dBm Output 2nd Order Inter- IM2 is Measured at f 10MHz 73.6dBm 58.8dBm 58.5dBm 61.1dBm LO cept rd Output 3 Order Intercept IM3 is Measured at f 3.5MHz and f 6.5MHz LO LO LINOPT pin floating 31.3dBm 30.3dBm 30.9dBm 29.2dBm LINOPT pin voltage optimized for best OIP3 35.1dBm 32.7dBm 35.1dBm 39.5dBm RF Output Noise Floor No Baseband AC Input Signal (6MHz offset) -161.6dBm/Hz -160.6dBm/Hz -160.6dBm/Hz -160.5dBm/Hz Image Rejection Without nulling (unadjusted) -45.5dBc -54.4dBc -56.6dBc -48.8dBc LO Feedthrough Without nulling (unadjusted) -43.1dBm -40.9dBm -39.6dBm -35.5dBm 2