Chip Directional Couplers for Wireless Applications
Toko America Inc.
Mt. Prospect, IL
Numerous circuit locations exist in today's portable wireless telephones and equipment that require an RF sample voltage to be redirected to another part of the circuit. In the past, directional couplers were considered one of the more bulky components in the system. With the current emphasis on miniaturization and lower cost, it was inevitable that the classic directional coupler would be reconfigured to meet these new demands.
The PTHM1616C series directional couplers have been developed specifically for the most common wireless applications, including cellular; industrial, scientific and medical (ISM)-900 and ISM-2.4; personal digital cellular-1.5; PCS-1900; DCS-1800; Digital European Cordless Telephone; and personal 
handyphone system requirements. The couplers are supplied in chip form in an ultra-compact type 0606 package and utilize a proprietary ceramic multilayer material and process to ensure superior performance and reliability. The products are manufactured using a photolithography process to etch the striplines on a ceramic substrate. This process is the same one used to manufacture the company's two percent tight tolerance PTL2012 and PTL1608 chip inductor series.
The chip couplers feature a low 0.5 mm profile and a 1.60 x 1.60 mm footprint, as shown in Figure 1 . The units are designed to 
operate over the 800 to 2000 MHz frequency range with a 50 W input/output impedance and exhibit a low insertion loss of less than 0.2 dB (typ) and return loss of 18 dB (min), as shown in Figure 2 . Figure 3 shows the products' typical coupling and isolation performance vs. frequency. (An external 50 W isolation resistor is required at pin 1.) Table 1 lists the performance specifications for four specific frequency ranges within the series.
|
Table I | ||||
|
|
PTHM1616C |
PTHM1616C |
PTHM1616C |
PTHM1616C |
|
Frequency Range (MHz) |
800 to 1000 |
1400 to 1600 |
1600 to 1800 |
1800 to 2000 |
|
Insertion Loss (dB)(max) |
0.25 |
0.30 |
0.35 |
0.35 |
|
Return Loss (dB) (min) |
18 |
18 |
18 |
18 |
|
Coupling (dB) |
20 ± 2 |
17 ± 2 |
15 ± 2 |
14 ± 2 |
|
Isolation (dB) (min) |
28 |
23 |
23 |
20 |
The units also feature a 3 W maximum power handling capability and are designed to operate over a -25° to +80°C temperature range. Storage temperature is from -40° to +85°C. The chip couplers are designed specifically for solder flow and reflow attachment and are packaged on 4000-piece reels for automated assembly.
Toko America Inc.,
Mt. Prospect, IL
(847) 297-0070.