BB208-02,135 - 10V Low Voltage Varactor Diode | NXP Semiconductors
MPN: BB208-02,135 ✓ Hoạt độngBB208-02,135 Tóm tắt
A varactor diode, also called a variable capacitance diode or varicap, is a semiconductor device that exploits the voltage-dependent depletion-layer capacitance of a reverse-biased PN junction. Within the power and signal-chain hierarchy, it belongs to the discrete semiconductor family and functions as a voltage-controlled capacitor for tuning circuits, sitting alongside other RF passives such as inductors and fixed capacitors in the front end of tuners, oscillators and filters.
Key features of the BB208-02 include excellent CV linearity for predictable tuning curves, a high capacitance ratio enabling wide tuning ranges from a small control-voltage swing, and very low series resistance which preserves Q factor in resonant circuits. The ultra-small SOD-523 footprint conserves PCB area in compact RF assemblies such as antenna tuners and VCO modules.
Technically, the planar epitaxial structure provides a sharp, repeatable junction profile, delivering a smooth capacitance-versus-voltage characteristic that simplifies linearizing circuitry in PLL-based frequency synthesizers. Distributor listings such as Utmel and FindIC confirm the single-diode configuration, 2 terminations and dual flat terminal form.
Typical applications include voltage-controlled oscillators (VCOs), electronically tuned LC filters, RF tuner bandpass circuits, and PLL loop tuning elements in communication equipment operating at low supply voltages.
In design, keep the tuning-voltage source low-noise and well decoupled, since varactor bias noise appears directly as oscillator phase noise; also observe the 10 V peak reverse voltage limit.
This page synthesizes distributor pricing, availability, and drop-in alternative analysis not found in the manufacturer datasheet, providing an engineering-oriented selection resource.
Bộ thay thế dễ dàng lắp đặt cho BB208-02,135 — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với BB208-02,135 (cùng hình factor và footprint) — khác nhau ở Device Type, Operating Temperature Range, Package, Packaging.
BB208-02,115
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →BB208-02,125
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
BB208-02,135 Tỷ lệ tối đa & tính chất điện
| Device Type | Variable capacitance diode (varactor) |
| Configuration | Single diode |
| Maximum Reverse Voltage | 10 V |
| Nominal Capacitance | 5.4 pF @ 7.5 V, 1 MHz |
| Capacitance Ratio | 5.2 (C1/C7.5) |
| Continuous Forward Current | 20 mA |
| Diode Capacitance (Ct) | 19.9 pF |
| Technology | Planar silicon |
| CV Linearity | Excellent (per datasheet) |
| Khoảng nhiệt độ hoạt động | -55C to +125C |
| Hộp | SOD-523 (SC-79) SMD plastic |
| Số lượng chân | 2 |
| Kiểu lắp đặt | Surface Mount |
| Packaging | Tape & Reel (7 inch reel) |
| Minimum Order Quantity | 3000 |
Cấu hình chân BB208-02,135
| Chân 1 | Cathode — Cathode terminal - connect to tuning (reverse bias) voltage node |
| Chân 2 | Anode — Anode terminal - connect to RF tank circuit node |
Ứng dụng tiêu biểu
BB208-02,135 phù hợp cho 6 Áp dụngs: Voltage-Controlled Oscillators (VCOs), PLL Frequency Synthesizers, Electronically Tuned LC Filters, RF Tuner Front Ends, Antenna Matching / Tuning Networks, Test and Measurement Instruments.
Voltage-Controlled Oscillators (VCOs)
The BB208-02,135 is well suited to VCO tank circuits because its 5.2 capacitance ratio (C1/C7.5) gives a wide frequency-tuning range from a modest 0-10 V control swing, and its very low series resistance preserves tank Q for low phase noise. In a typical LC VCO, the varactor is DC-biased at its cathode via a 47k resistor and AC-coupled into the inductor tank with a 1-10 nF blocking capacitor. Because its 5.4 pF mid-bias capacitance keeps the tank impedance manageable at VHF/UHF frequencies, designers achieve tuning slopes compatible with PLL charge-pump outputs. The excellent CV linearity of the planar structure also simplifies loop-gain compensation across the tuning band.
Được đề xuất
PLL Frequency Synthesizers
In PLL-based frequency synthesizers, the BB208-02,135 acts as the tuning element that converts charge-pump error voltage into oscillator frequency correction. Its excellent CV linearity means loop gain varies less across the band, easing loop-filter design and maintaining stable bandwidth. The 10 V maximum reverse voltage accommodates charge pumps operating from higher rails, while the -55C to +125C junction range covers industrial synthesizer environments. Placed directly across the VCO tank inductor with a 10-100k bias resistor, the varactor's low series resistance minimizes added phase-noise degradation. The SOD-523 package keeps parasitic inductance low, which matters for UHF bands where even 1 nH of series inductance shifts the tuning curve.
Được đề xuất
Electronically Tuned LC Filters
Varactors such as the BB208-02,135 enable voltage-programmable bandpass and lowpass filters by replacing mechanical or switched capacitor banks. The 5.2 capacitance ratio allows roughly a 2x shift in filter corner frequency across the 1-7.5 V bias range, while excellent CV linearity keeps passband shape predictable as tuning voltage changes. Its very low series resistance limits the insertion-loss penalty in high-Q LC resonators. In design, place the varactor in series with the filter inductor and couple the control node through a large-value resistor so RF swing does not rectify across the junction. The SOD-523 footprint supports dense filter arrays in channelized receivers and test equipment.
Được đề xuất
RF Tuner Front Ends
Low-voltage tuner front ends for broadcast receivers use varactors like the BB208-02,135 to tune input bandpass and local-oscillator stages from a common control voltage. The device's high capacitance ratio covers wide band segments without band switching, and the 10 V rating matches standard tuner tuning rails. NXP's low-voltage design intent means the CV curve is optimized for tuning voltage sources derived from 5 V or 12 V supplies with simple dividers. The ultra-small SOD-523 package suits compact module tuners where board area is constrained. Because front-end Q directly affects image rejection, the varactor's low series resistance is a key selection parameter in these designs.
Được đề xuất
Antenna Matching / Tuning Networks
Adaptive antenna matching networks use varactors to keep antenna VSWR optimized across frequency, load, and hand-position changes in portable and IoT radios. The BB208-02,135 provides voltage-controlled reactance in pi or L matching sections; its 5.4 pF nominal capacitance and 5.2 ratio give sufficient matching-range coverage for compact antennas operating in VHF through UHF bands. Low series resistance is critical here because matcher loss directly reduces transmitter efficiency and battery life. The -55C to +125C operating range tolerates outdoor and vehicular environments. Control circuits should be noise-filtered, since bias noise modulates the match and can create spurious emissions in adjacent channels.
Được đề xuất
Test and Measurement Instruments
Signal generators, sweep oscillators, and tracking generators in test equipment employ varactors like the BB208-02,135 for electronically swept tuning. The planar device's repeatable, low-hysteresis CV characteristic ensures calibration stability between service intervals, and its -55C to +125C range survives instrument warm-up and harsh lab transport conditions. Sweep circuits can drive the varactor from 0 V to just under 10 V for maximum span, with the 5.2 ratio delivering greater than an octave of frequency coverage in a simple LC oscillator. Very low series resistance supports the high-Q tanks needed for low close-in phase noise in reference-grade sources. SOD-523 mounting simplifies automated assembly of oscillator modules.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho BB208-02,135 — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | BB208-02,115 | BB208-02,125 |
|---|---|---|---|
| Package | SOD-523 (SC-79) | SOD-523 (SC-79) - same | SOD-523 (SC-79) - same |
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Configuration | Single varactor | Single varactor | Single varactor |
| Maximum Reverse Voltage | 10 V | 10 V | 10 V |
| Diode Capacitance (Ct) | 19.9 pF | 19.9 pF | 19.9 pF |
| Capacitance Ratio | 5.2 (C1/C7.5) | 5.2 (C1/C7.5) | 5.2 (C1/C7.5) |
| Operating Temperature | -55C to +125C | -55C to +125C | -55C to +125C |
Bảo phân biệt quan trọng
- High capacitance ratio of 5.2 for wide tuning range (vsBB208-03,115)
- Excellent CV linearity simplifies PLL loop design (vsGeneric varactor substitutes)
- Ultra-small SOD-523 footprint saves board area (vsBB208-03,115 (SOD-323))
Ghi chú thiết kế
Tuning-voltage noise appears directly as oscillator phase noise because any ripple on the BB208-02,135 bias modulates its junction capacitance. Filter the control line with an RC network (e.g., 10k series resistor plus 100 nF to ground) placed close to the varactor cathode, and keep high-frequency digital traces away from the tuning node. Use a low-noise reference or DAC output for the tuning source; a charge-pump PLL output should pass through a loop filter sized for low spurious content.
Respect the 10 V maximum reverse voltage: transient excursions above breakdown damage the junction and permanently alter the CV curve. Also ensure the RF swing across the diode does not forward-bias it on negative peaks - keep peak-to-peak tank voltage below roughly twice the DC bias to avoid rectification distortion and harmonics. Large RF swings cause capacitance pumping, generating sidebands in VCOs. If needed, split the tank with two series varactors to halve per-device RF stress.
Minimize series inductance by placing the BB208-02,135 directly across the tank inductor pads; at UHF even the small SOD-523 parasitics (~0.5-1 nH) shift the tuning characteristic. Keep ground return paths short and connect the anode side to a solid RF ground plane. Because this part is a maturing product with 99-week factory lead time, add a second footprint-compatible pad pattern (identical SOD-523) so the BB208-02,115 or a verified equivalent can be substituted without PCB respin.
Thông tin tuân thủ
Compliance status was not stated in the provided web data. NXP typically marks the ,135 suffix as RoHS-compliant (suffix code convention), but this must be confirmed against the official NXP compliance documentation before assuming.
